Hormone receptor mRNA and protein levels as predictors of premenopausal tamoxifen benefit

BACKGROUND AND PURPOSE

Tamoxifen remains an important adjuvant treatment in premenopausal patients with hormone receptor-positive breast cancer. Thus, determination of hormone receptors is important. Here, we compare cytosol-based methods, immunohistochemistry (IHC), and gene expression (GEX) analysis for determining hormone receptor status in premenopausal breast cancer patients from a randomised tamoxifen trial, to evaluate their performance in identifying patients that benefit from tamoxifen.

PATIENTS AND METHODS

Premenopausal patients (n=564) were randomised to 2 years of tamoxifen or no systemic treatment. Estrogen receptor (ER) and progesterone receptor (PR) status by protein expression measured by cytosol-based methods and IHC, and mRNA by GEX analysis were compared in 313 patients with available data from all methods. Kaplan Meier estimates and Cox regression were used to evaluate the treatment-predictive value for recurrence-free interval (RFi) and overall survival (OS). Median follow-up for event-free patients was 26 (RFi) and 33 (OS) years.

RESULTS

The mRNA data of ESR1 and PGR distributed bimodally, patterns confirmed in an independent cohort. Kappa-values between all methods were 0.76 and 0.79 for ER and PR, respectively. Tamoxifen improved RFi in patients with ER-positive (ER+) or PR-positive (PR+) tumours (Hazard Ratio [HR] and 95% confidence interval [CI]), cytosol-ER+ 0.53 [0.36-0.79]; IHC-ER+ 0.55 [0.38-0.79]; GEX-ER+ 0.54 [0.37-0.77]; cytosol-PR+ 0.49 [0.34-0.72]; IHC-PR+ 0.58 [0.40-0.85]; GEX-PR+ 0.55 [0.38-0.80]). Results were similar for OS.

INTERPRETATION

These methods can all identify patients that benefit from 2 years of tamoxifen with equal performance, indicating that GEX data might be used to guide adjuvant tamoxifen therapy.

Breast cancer survival and incidence of second primary cancers after 30 years in a randomized study of two versus five years of adjuvant tamoxifen therapy

BACKGROUND

Tamoxifen is an established treatment for breast cancer, but its long-term effects on survival and on secondary cancers are not fully evaluated.

MATERIAL AND METHODS

We studied 30 years outcome of 4124 postmenopausal patients who were randomized to receive (totally) two or five years of adjuvant tamoxifen.

RESULTS

After 5 years of follow-up, when tamoxifen treatment was finished in both groups, until 15 years of follow-up, overall mortality (HR 0.80, 95% CI 0.72-0.90, p < 0.001), breast cancer mortality for all patients (HR 0.80, 95% CI 0.68-0.94, p = 0.006) and breast cancer mortality for patients with estrogen receptor positive disease (HR 0.67, 95% CI 0.55-0.83, p < 0.001) were significantly reduced in the five-year group as compared to the two-year group. After 15 years, the difference remained but did not further increase. In the five-year group, the incidence of contralateral breast cancer was gradually reduced during the entire period of observation. The incidence of lung cancer was also reduced in the five-year group. In contrast there was an increased endometrial cancer incidence in the five-year group and for those receiving 40 mg of tamoxifen this incidence was further increased.

CONCLUSION

Three more years of tamoxifen therapy reduced the risk of breast cancer mortality. The difference was established during the first 15 years after randomization. Moreover, the incidence of contralateral breast cancer gradually decreased for 30 years. The incidence of lung cancer was reduced in the five-year group. In contrast the incidence of endometrial cancer was increased.

Tamoxifen-predictive value of gene expression signatures in premenopausal breast cancer: data from the randomized SBII:2 trial

BACKGROUND

Gene expression (GEX) signatures in breast cancer provide prognostic information, but little is known about their predictive value for tamoxifen treatment. We examined the tamoxifen-predictive value and prognostic effects of different GEX signatures in premenopausal women with early breast cancer.

METHODS

RNA from formalin-fixed paraffin-embedded tumor tissue from premenopausal women randomized between two years of tamoxifen treatment and no systemic treatment was extracted and successfully subjected to GEX profiling (n = 437, NanoString Breast Cancer 360™ panel). The median follow-up periods for a recurrence-free interval (RFi) and overall survival (OS) were 28 and 33 years, respectively. Associations between GEX signatures and tamoxifen effect were assessed in patients with estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+ /HER2-) tumors using Kaplan-Meier estimates and Cox regression. The prognostic effects of GEX signatures were studied in the entire cohort. False discovery rate adjustments (q-values) were applied to account for multiple hypothesis testing.

RESULTS

In patients with ER+/HER2- tumors, FOXA1 expression below the median was associated with an improved effect of tamoxifen after 10 years with regard to RFi (hazard ratio [HR]FOXA1(high) = 1.04, 95% CI = 0.61-1.76, HRFOXA1(low) = 0.30, 95% CI = 0.14-0.67, qinteraction = 0.0013), and a resembling trend was observed for AR (HRAR(high) = 1.15, 95% CI = 0.60-2.20, HRAR(low) = 0.42, 95% CI = 0.24-0.75, qinteraction = 0.87). Similar patterns were observed for OS. Tamoxifen was in the same subgroup most beneficial for RFi in patients with low ESR1 expression (HRRFi ESR1(high) = 0.76, 95% CI = 0.43-1.35, HRRFi, ESR1(low) = 0.56, 95% CI = 0.29-1.06, qinteraction = 0.37). Irrespective of molecular subtype, higher levels of ESR1, Mast cells, and PGR on a continuous scale were correlated with improved 10 years RFi (HRESR1 = 0.80, 95% CI = 0.69-0.92, q = 0.005; HRMast cells = 0.74, 95% CI = 0.65-0.85, q < 0.0001; and HRPGR = 0.78, 95% CI = 0.68-0.89, q = 0.002). For BC proliferation and Hypoxia, higher scores associated with worse outcomes (HRBCproliferation = 1.54, 95% CI = 1.33-1.79, q < 0.0001; HRHypoxia = 1.38, 95% CI = 1.20-1.58, q < 0.0001). The results were similar for OS.

CONCLUSIONS

Expression of FOXA1 is a promising predictive biomarker for tamoxifen effect in ER+/HER2- premenopausal breast cancer. In addition, each of the signatures BC proliferation, Hypoxia, Mast cells, and the GEX of AR, ESR1, and PGR had prognostic value, also after adjusting for established prognostic factors. Trial registration This trial was retrospectively registered in the ISRCTN database the 6th of December 2019, trial ID: https://clinicaltrials.gov/ct2/show/ISRCTN12474687 .

Abstract P2-03-04: Long-Term Benefit from Adjuvant Tamoxifen in Luminal A and Luminal B Breast Cancer Patients

Background: The risk for patients with estrogen receptor (ER)-positive breast cancer remains stable decades after primary diagnosis, with a large proportion of distant metastatic events occurring late. Thus, long-term follow-up studies are essential to understand true treatment benefit. Tamoxifen (TAM) therapy is a fundamental endocrine treatment for ER-positive breast cancer. We have previously shown a long-term tamoxifen therapy benefit for patients with less aggressive tumor characteristics in ER-positive/HER2-negative patients. However, ER-positive breast cancer is highly heterogenous and can be separated into different molecular subpopulations that behave differently during extended follow-up. The long-term tamoxifen benefit by molecular subtype is largely unexplored. We therefore aimed to investigate the long-term benefit from tamoxifen by clinically used tumor characteristics in Luminal A vs Luminal B patients in the Stockholm tamoxifen (STO)-trials with complete 20-years follow-up.

Methods: Secondary analysis of ER-positive/HER2-negative patients with Luminal A or B molecular subtype (n=952) from the STO-trials (1976-1997) randomized to TAM (40 mg) vs no endocrine therapy (control). Gene expression data was generated using custom designed Agilent arrays from FFPE breast cancer tumor tissue and was used to define PAM50 molecular subtypes. The clinically used markers were reannotated in 2014 and 2020. Complete 20-year follow-up was obtained from Swedish high-qualitative registries. The long-term distant recurrence-free interval (DRFI) was assessed by Kaplan-Meier, multivariable Cox proportional hazard regression and time-varying analysis, using flexible parametric modelling.

Results: Multivariable analysis showed significantly improved long-term DRFI from TAM vs control for both Luminal A (HR=0.59; 95% CI, 0.44-0.81) and Luminal B (HR=0.67; 95% CI, 0.46-0.99) patients. Time-varying analysis showed that patients with Luminal A subtype significantly benefitted from TAM for 15 years (HR=0.60, 95% CI, 0.39-0.94 at year 15), whereas patients with Luminal B subtype had a significant TAM benefit for 5 years (HR=0.64, 95% CI, 0.42-0.98 at year 5), see Table. Furthermore, a significant long-term TAM benefit for patients with large tumor size (pT&gt;20mm: HR=0.46; 95% CI, 0.25-0.84), tumor grade 1-2 (HR=0.55; 95% CI, 0.40-0.77), lymph node-negative (HR=0.51, 95% CI, 0.34-0.78), PR-positive (HR=0.57, 95% CI, 0.40-0.81) and Ki-67-low tumors (HR=0.55, 95% CI, 0.39-0.77) was seen for Luminal A patients. In Luminal B patients, significantly improved long-term DRFI from TAM vs control was seen for small tumor size (pT≤20mm: HR=0.44; 95% CI, 0.24-0.80), tumor grade 1-2 (HR=0.51; 95% CI, 0.29-0.90), lymph node-negative (HR=0.40, 95% CI, 0.19-0.83), PR-positive (HR=0.59, 95% CI, 0.38-0.93) and Ki-67-low tumors (HR=0.45, 95% CI, 0.25-0.84).

Conclusions: This study suggests a 15 years tamoxifen benefit for patients with Luminal A subtype tumors, whereas the benefit for patients with Luminal B tumors is up to five years after diagnosis. Furthermore, our study suggests a long-term tamoxifen benefit for patients with less aggressive tumor characteristics regardless of tumor subtype, except for tumor size in Luminal A patients. ER-positive breast cancer is a heterogeneous disease and long-term follow-up studies in molecular subtypes are essential to understand differences in treatment benefit.

Table. Time-varying analysis of long-term tamoxifen therapy benefit by PAM50 molecular subtype.

Time-varying analysis of distant recurrence-free interval (DRFI) to assess how tamoxifen benefit varied over the 20 year of follow-up using flexible parametric survival modelling. Patients included in analyses with no missing values. Estimated hazard ratios (HR) at year 5, 10, 15 and 20 for patients with Luminal A or Luminal B molecular subtype tumors randomized to tamoxifen therapy, as compared with patients randomized to no endocrine therapy (control). Adjusted for age, period of primary breast cancer diagnosis, tumor size, tumor grade, lymph node status, PR status, Ki-67 status, chemotherapy, radiotherapy, type of surgery, and menopausal status. *indicates significant findings P&lt;0.05

Citation Format: Huma Dar, Annelie Johansson, Anna Nordenskjöld, Gizeh Perez-Tenorio, Christina Yau, Christopher C. Benz, Laura J. Esserman, Bo Nordenskjöld, Olle Stål, Tommy Fornander, Linda S. Lindström. Long-Term Benefit from Adjuvant Tamoxifen in Luminal A and Luminal B Breast Cancer Patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-03-04.

Abstract P3-05-03: Long-term survival and intra-tumor heterogeneity of progesterone receptor expression in estrogen receptor-positive/progesterone receptor-positive premenopausal women with breast cancer

Background: Women with estrogen receptor (ER)-positive disease have a long-term risk of distant recurrence. The poor survival of premenopausal women diagnosed with breast cancer combined with the otherwise long life expectancy makes it especially important to identify tumor characteristics associated with long-term survival. Intra-tumor heterogeneity, having cancer cells of varying characteristics across the tumor, may promote therapeutic resistance and metastatic capacity. We have previously shown that high intra-tumor heterogeneity of ER increases the risk of fatal breast cancer. To our knowledge, the relation between intra-tumor heterogeneity of progesterone receptor (PR) expression and long-term survival is not known. We aimed to study the association between intra-tumor heterogeneity of PR and long-term survival of premenopausal women in the Stockholm tamoxifen trial (STO-5), with 20-years complete follow-up.

Methods: This study was a secondary analysis of 504 ER-positive/PR-positive premenopausal women from the STO-5 trial (1990-1997). 451 women had human epidermal growth factor receptor 2 (HER2)-negative tumors. Patients were randomized to receive either 2 years of endocrine treatment (tamoxifen and/or goserelin) or no endocrine treatment. Lymph node-positive patients (n=251) also received standard chemotherapy (CMF). Immunohistochemical analysis, including estimating the proportion of tumor cells for each PR intensity level (0, 1+, 2+, or 3+), was completed in 2020. Intra-tumor heterogeneity of PR was calculated using Rao’s quadratic entropy and then categorized into low and high intra-tumor heterogeneity groups, using a predefined cutoff at the second tertile. Complete long-term (20 year) follow-up was obtained from high-quality Swedish registries. Long-term distant recurrence-free interval (DRFI) was assessed using univariate Kaplan-Meier analysis and multivariable Cox proportional hazard modeling, adjusting for patient and tumor characteristics.

Results: A statistically significant difference in 20-year DRFI was seen between patients with high and low intra-tumor heterogeneity of PR in the univariate Kaplan-Meier analysis (log-rank P&lt; 0.01). Survival proportions for DRFI at 20 years were 60.2% (95% CI, 53.2%-68.1%) and 73.3% (95% CI, 68.6%-78.3%) for patients with high and low PR intra-tumor heterogeneity, respectively. Analysis in patients with HER2-negative tumors yielded similar results. In the multivariable analysis, women with high intra-tumor heterogeneity of PR had a significantly increased long-term risk of distant recurrence, compared to women with low intra-tumor heterogeneity, hazard ratio (HR)=1.49 (95% CI, 1.08-2.06). The same pattern was seen in HER2-negative women, HR=1.50 (95% CI, 1.06-2.12), see Table.

Conclusions: This study suggests an increased long-term risk of distant recurrences in ER-positive/PR-positive premenopausal women with high intra-tumor heterogeneity of PR as compared to women with low intra-tumor heterogeneity of PR, independent of HER2 status. Ongoing analyses include using deep learning for image analysis of breast cancer tumors to examine intra-tumor heterogeneity at higher resolution and for various tumor characteristics. Better understanding of tumor characteristics associated with long-term risk in premenopausal women is needed, given the poor prognosis and early onset of the disease.

Long-term risk of distant recurrence by PR intra-tumor heterogeneity and HER2 status Multivariable Cox proportional hazard regression modeling of 20-year distant recurrence-free interval (DRFI) by high and low PR intra-tumor heterogeneity. ER-positive/PR-positive and ER-positive/PR-positive/HER2-negative premenopausal women were analyzed separately. The crude model was adjusted for age, randomization year, lymph node status, and endocrine treatment. The full model was adjusted for age, randomization year, lymph node status, endocrine treatment, tumor size, Ki-67 status, and HER2 status.

Citation Format: Oscar Danielsson, Huma Dar, Gizeh Perez-Tenorio, Anna Nordenskjöld, Christina Yau, Christopher C. Benz, Laura J. Esserman, Bo Nordenskjöld, Olle Stål, Tommy Fornander, Annelie Johansson, Linda S. Lindström. Long-term survival and intra-tumor heterogeneity of progesterone receptor expression in estrogen receptor-positive/progesterone receptor-positive premenopausal women with breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-03.

Twenty-Year Benefit From Adjuvant Goserelin and Tamoxifen in Premenopausal Patients With Breast Cancer in a Controlled Randomized Clinical Trial

PURPOSE

To assess the long-term (20-year) endocrine therapy benefit in premenopausal patients with breast cancer.

METHODS

Secondary analysis of the Stockholm trial (STO-5, 1990-1997) randomly assigning 924 premenopausal patients to 2 years of goserelin (3.6 mg subcutaneously once every 28 days), tamoxifen (40 mg orally once daily), combined goserelin and tamoxifen, or no adjuvant endocrine therapy (control) is performed. Random assignment was stratified by lymph node status; lymph node-positive patients (n = 459) were allocated to standard chemotherapy (cyclophosphamide, methotrexate, and fluorouracil). Primary tumor immunohistochemistry (n = 731) and gene expression profiling (n = 586) were conducted in 2020. The 70-gene signature identified genomic low-risk and high-risk patients. Kaplan-Meier analysis, multivariable Cox proportional hazard regression, and multivariable time-varying flexible parametric modeling assessed the long-term distant recurrence-free interval (DRFI). Swedish high-quality registries allowed a complete follow-up of 20 years.

RESULTS

In estrogen receptor-positive patients (n = 584, median age 47 years), goserelin, tamoxifen, and the combination significantly improved long-term distant recurrence-free interval compared with control (multivariable hazard ratio [HR], 0.49; 95% CI, 0.32 to 0.75, HR, 0.57; 95% CI, 0.38 to 0.87, and HR, 0.63; 95% CI, 0.42 to 0.94, respectively). Significant goserelin-tamoxifen interaction was observed (P = .016). Genomic low-risk patients (n = 305) significantly benefitted from tamoxifen (HR, 0.24; 95% CI, 0.10 to 0.60), and genomic high-risk patients (n = 158) from goserelin (HR, 0.24; 95% CI, 0.10 to 0.54). Increased risk from the addition of tamoxifen to goserelin was seen in genomic high-risk patients (HR, 3.36; 95% CI, 1.39 to 8.07). Moreover, long-lasting 20-year tamoxifen benefit was seen in genomic low-risk patients, whereas genomic high-risk patients had early goserelin benefit.

CONCLUSION

This study shows 20-year benefit from 2 years of adjuvant endocrine therapy in estrogen receptor-positive premenopausal patients and suggests differential treatment benefit on the basis of tumor genomic characteristics. Combined goserelin and tamoxifen therapy showed no benefit over single treatment. Long-term follow-up to assess treatment benefit is critical.

Long-term follow-up of early stage HER2-positive breast cancer patients treated with trastuzumab: A population-based real world multicenter cohort study

Introduction

Since its introduction in standard of care, trastuzumab has revolutionized the treatment of patients with early and late stages of HER2-positive breast cancer. While the initial clinical trials were convincing and lead to major changes in practice, more knowledge on the long-term outcome and tolerability is needed. The present study was designed to assess the survival, prognostic factors and relapse patterns after the implementation of trastuzumab in a real-world cohort.

Methods

All cases of HER2-positive breast cancer diagnosed between 2006 and 2014 in the Southeast Healthcare Region of Sweden were retrospectively identified. Medical records were thoroughly reviewed with regard to clinicopathological parameters, treatments, relapse pattern and adverse events.

Results

643 patients were identified and 599 were eligible for analysis. Breast cancer specific survival, distant recurrence free survival and local recurrence free survival were 93.4%, 89.7% and 98.0% for trastuzumab treated patients and 87.4%, 81.6% and 87.4% in patients not treated with trastuzumab, respectively. ER status, nodal status and trastuzumab treatment were all independent prognostic factors in multivariable analysis. No new safety concerns were discovered.

Conclusion

The real-world outcome of trastuzumab-treated patients with early HER2-positive breast cancer is similar to what has been previously reported in long-term follow up of prospective clinical trials. ER status, nodal status and trastuzumab treatment are independent prognostic factors for breast cancer specific mortality rate, distant recurrence rate and locoregional recurrence rate in HER2-positive patients in the trastuzumab era.

PAM50 subtyping and ROR score add long-term prognostic information in premenopausal breast cancer patients

PAM50 intrinsic subtyping and risk of recurrence (ROR) score are approved for risk profiling in postmenopausal women. We aimed to examine their long-term prognostic value in terms of breast cancer-free interval (BCFi) and overall survival (OS) (n = 437) in premenopausal women randomised to 2 years of tamoxifen versus no systemic treatment irrespective of hormone-receptor status. Intrinsic subtyping added independent prognostic information in patients with oestrogen receptor-positive/human epidermal growth factor 2-negative tumours for BCFi and OS after maximum follow-up (overall P-value 0.02 and 0.006, respectively) and those with high versus low ROR had worse prognosis (maximum follow-up: hazard ratio (HR)_BCFi: 1.70, P = 0.04). The prognostic information by ROR was similar regarding OS and in multivariable analysis. These results support that PAM50 subtyping and ROR score provide long-term prognostic information in premenopausal women. Moreover, tamoxifen reduced the incidence of breast cancer events only in patients with Luminal A_PAM50 tumours (0–10 years: HR_{BCFi(Luminal A)}: 0.41, HR_{BCFi(Luminal B)}: 1.19, P_interaction = 0.02).

Trial registration: This trial is registered in the ISRCTN database, trial ID: ISRCTN12474687.

Clinical and Molecular Characteristics of ER-Positive Ultralow Risk Breast Cancer Tumors Identified by the 70-Gene Signature

The metastatic potential of estrogen receptor (ER)-positive breast cancers is heterogenous and distant recurrences occur months to decades after primary diagnosis. We have previously shown that patients with tumors classified as ultralow risk by the 70-gene signature have a minimal long-term risk of fatal breast cancer. Here, we evaluate the previously unexplored underlying clinical and molecular characteristics of ultralow risk tumors in 538 ER-positive patients from the Stockholm tamoxifen randomized trial (STO-3). Out of the 98 ultralow risk tumors, 89% were luminal A molecular subtype, whereas 26% of luminal A tumors were of ultralow risk. Compared with other ER-positive tumors, ultralow risk tumors were significantly (Fisher's test, P<0.05) more likely to be of smaller tumor size, lower grade, progesterone receptor (PR)-positive, human epidermal growth factor 2 (HER2)-negative and have low Ki-67 levels (proliferation-marker). Moreover, ultralow risk tumors showed significantly lower expression scores of multi-gene modules associated with the AKT/mTOR-pathway, proliferation (AURKA), HER2/ERBB2-signaling, IGF1-pathway, PTEN-loss, and immune response (IMMUNE1 and IMMUNE2), and higher expression scores of the PIK3CA-mutation-associated module. Furthermore, 706 genes were significantly (FDR<0.001) differentially expressed in ultralow risk tumors, including lower expression of genes involved in immune response, PI3K/Akt/mTOR-pathway, histones, cell cycle, DNA repair, apoptosis, and higher expression of genes coding for epithelial-to-mesenchymal transition, and homeobox proteins, among others. In conclusion, ultralow risk tumors, associated with minimal long-term risk of fatal disease, differ from other ER-positive tumors, including luminal A molecular subtype tumors. Identification of these characteristics is important to improve our prediction of non-fatal versus fatal breast cancer. This article is protected by copyright. All rights reserved.

Abstract PD9-05: Prognostic and tamoxifen-predictive effect of PAM50 and ROR score in premenopausal women included in the randomised SBII:2 trial

PURPOSE The Luminal intrinsic subtypes and Luminal-like surrogate subtypes of breast cancer are based on gene expression and pathological markers, respectively. We aimed to study the prognostic value of PAM50 intrinsic subtypes and risk of recurrence (ROR) score in premenopausal women with early breast cancer. Prognostic differences of Luminal PAM50 vs. surrogate subtyping, and the predictive effect of Luminal PAM50 subtypes on tamoxifen benefit were further evaluated. METHODS PAM50 intrinsic subtypes and ROR score (n = 437) were determined by gene expression analyses (NanoString’s Breast Cancer 360 TM assay (BC360)) after RNA isolation of breast cancer tissues from patients included in the randomised SBII:2pre trial. Premenopausal women were randomised between two years of adjuvant tamoxifen vs. control. Surrogate subtyping was performed according to the St. Gallen 2013 classification. The endpoints breast cancer-free interval (BCFi) and overall survival (OS) (median follow-up: 28 and 33 years, respectively) were evaluated using the maximum follow-up and the two disjoint time intervals 0-10 years and &gt;10 years. RESULTS After maximum follow-up, patients with Luminal B tumours by PAM50 subtyping had worse prognosis as compared to those with Luminal A tumours (Hazard ratio (HR)BCfi 1.60; 95% confidence interval (CI) 1.17-2.18; P = 0.004; Table 1). For this time interval, high vs. low ROR score was associated with higher incidence of breast cancer events (HRBCFi 1.70; 95% CI 1.01-2.85; P = 0.04), with a similar trend seen in node-negative patients. In total, 58% of tumours classified as Luminal B-like by surrogate subtyping were re-classified into Luminal A by PAM50 subtyping. At 10 years follow-up, patients whose tumours were classified as Luminal B-like/Luminal A, had a better prognosis as compared to those uniformly classified as Luminal B-like/Luminal B (HRBCFi 0.52; 95% CI 0.33-0.83; P = 0.006) but the effect weakened with longer follow-up (Table 1). According to 10 years data, the incidence of breast cancer events was reduced by two thirds by tamoxifen in patients with PAM50 Luminal A tumours, while no effect was seen in those with Luminal B tumours (HRBCFi 0.41 and HRBCFi 1.19, respectively, (Pinteraction = 0.02); Table 2). CONCLUSIONS PAM50 and ROR score provided prognostic information also in premenopausal women. More than 50% of patients with Luminal B-like tumours defined by surrogate subtyping were re-classified as Luminal A according to PAM50 subtyping. These patients had an improved prognosis at 10 years of follow-up, but the effect attenuated with time. At 10 years, PAM50 Luminal A, but not Luminal B, intrinsic subtype was associated with tamoxifen benefit.

Table 1.Prognostic effect of PAM50 intrinsic subtypes and St. Gallen 2013 surrogate subtyping regarding BCFi and OS for different time intervals (uni- and multivariable analyses)UnivariableMultivariableaBCFiOSBCFiOSHR (95% CI); P valuePAM50 intrinsic subtype0–10 years(n = 437, n = 218 events)(n = 437, n = 176 events)(n = 411, n = 203 events)(n = 411, n = 166 events)LumA (Ref.)1.001.001.001.00LumB1.88 (1.31–2.71); 0.0012.33 (1.52–3.58); &lt;0.0011.78 (1.18–2.68); 0.0062.08 (1.28–3.38); 0.003HER2-E2.55 (1.77–3.69); &lt;0.0014.08 (2.70–6.18); &lt;0.0011.99 (1.23–3.24); 0.0052.94 (1.71–5.03); &lt;0.001Basal-like2.09 (1.45–2.99); &lt;0.0013.36 (2.23–5.06); &lt;0.0011.95 (1.19–3.22); 0.0083.00 (1.73–5.22); &lt;0.001&gt;10 yearsb(n = 210, n = 68 events)(n = 261, n = 124 events)(n = 199, n = 66 events)(n = 245, n = 119 events)LumA (Ref.)1.001.001.001.00LumB1.05 (0.55–2.00); 0.890.85 (0.52–1.39), 0.501.92 (0.92–4.01); 0.081.16 (0.66–2.04); 0.62HER2-E0.51 (0.20–1.29); 0.150.70 (0.38–1.29); 0.251.27 (0.33–4.90): 0.731.77 (0.76–4.14); 0.19Basal-like0.95 (0.50–1.82); 0.880.69 (0.40–1.17); 0.172.58 (0.94–7.08); 0.071.90 (0.86–4.18); 0.11Maximum follow-up timec(n = 437, n = 286 events)(n = 437, n = 300 events)(n = 411, n = 269 events)(n = 411, n = 285 events)LumA (Ref.)1.001.001.001.00LumB1.60 (1.17–2.18); 0.0041.41 (1.03–1.93); 0.031.66 (1.17–2.37), 0.0051.48 (1.04–2.10); 0.03HER2-E1.84 (1.32–2.56); &lt;0.0011.99 (1.45–2.73); &lt;0.0011.81 (1.16–2.81); 0.0092.19 (1.43–3.36); &lt;0.001Basal-like1.69 (1.24–2-31), 0.0011.68 (1.24–2.28); 0.0011.92 (1.24–2.99); 0.0042.24 (1.45–3.45); &lt;0.001St. Gallen 2013 surrogate subtype/PAM50 intrinsic subtype0–10 years(n = 207, n = 87 events)(n = 207, n = 60 events)(n = 205, n = 87 events)(n = 205, n = 60 events)LumB-like/LumB (Ref.)1.001.001.001.00LumB-like/LumA0.52 (0.33–0.83); 0.0060.37 (0.21–0.66); 0.0010.50 (0.29–0.84), 0.0090.38 (0.20–0.74); 0.004LumA-like/LumB0.49 (0.12–2.05), 0.330.76 (0.18–3.20); 0.710.77 (0.18–3.32); 0.721.12 (0.25–5.07); 0.88LumA-like/LumA0.39 (0.21–0.73), 0.0030.32 (0.15–0.68); 0.0030.45 (0.23–0.91); 0.030.44 (0.19–1.02); 0.05&gt;10 yearsb(n = 117, n = 42 events)(n = 147, n = 70 events)(n = 115, n = 41 events)(n = 145, n = 70 events)LumB-like/LumB (Ref.)1.001.001.001.00LumB-like/LumA1.30 (0.62–2.69); 0.491.11 (0.62–1.98); 0.720.64 (0.26–1.60); 0.340.59 (0.30–1.15); 0.12LumA-like/LumB----LumA-like/LumA0.45 (0.16–1.23); 0.120.81 (0.41–1.59); 0.540.26 (0.08–0.80); 0.020.39 (0.18–0.84); 0.02Maximum follow-up timec(n = 207, n = 129 events)(n = 207, n = 130 events)(n = 205, n = 128 events)(n = 205, n = 130 events)LumB-like/LumB (Ref.)1.001.001.001.00LumB-like/LumA0.70 (0.47–1.02); 0.060.65 (0.44–0.96); 0.030.58 (0.37–0.90); 0.020.50 (0.32–0.79); 0.003LumA-like/LumB0.34 (0.08–1.41); 0.140.37 (0.09–1.52); 0.170.53 (0.12–2.24); 0.380.48 (0.11–2.05): 0.32LumA-like/LumA0.39 (0.23–0.67); 0.0010.51 (0.32–0.83); 0.0070.39 (0.24–0.70); 0.0020.43 (0.25–0.74); 0.003Abbreviations: BCFi, breast cancer free-interval; CI, confidence interval; HR, hazard ratio; Lum, Luminal; NHG, Nottingham histological grade; OS, overall survival; TAM, tamoxifenaAll analyses were stratified by study region and adjusted for age (continuous), tumour size (&gt;20 mm vs. ≤20), NHG (1 vs. 2 vs. 3), nodal status (N0 vs. N1 vs. N2) and treatment arm in addition to surrogate/molecular subtype b10 years–maximum follow-up time, starting at year 10c32 and 36 years regarding BCFi and OS, respectively

Table 2.Predictive value (univariable analyses) of Lum PAM50 intrinsic subtypes for TAM response with respect to BCFi and OS (ER-positive/HER2-negative cohort)BCFiOSHR (95% CI); P value0-10 years(n = 217, n = 92 events)(n = 217, n = 64 events)TAM vs. control in Lum A0.41 (0.23-0.74); 0.0030.61 (0.30-1.26); 0.18TAM vs. control in Lum B1.19 (0.63-2.27); 0.591.76 (0.85-3.63); 0.13Interaction Lum PAM50 subtype x TAM (HR ratio)0.34 (0.14-0.83); 0.020.35 (0.13-0.97); 0.04&gt;10 yearsa(n = 121, n = 43 events)(n = 153, n = 74 events)TAM vs. control in Lum A0.69 (0.35-1.37); 0.290.74 (0.44-1.25); 0.26TAM vs. control in Lum B0.17 (0.04-0.80); 0.030.25 (0.08-0.77); 0.02Interaction Lum PAM50 subtype x TAM (HR ratio)4.05 (0.74-22.1); 0.112.95 (0.85-10.2); 0.09Maximum follow-up timeb(n = 217, n = 135 events)(n = 217, n = 138 events)TAM vs. control in Lum A0.52 (0.34-0.81); 0.0040.71 (0.46-1.08); 0.11TAM vs. control in Lum B0.80 (0.45-1.41); 0.440.87 (0.49-1.54); 0.63Interaction Lum PAM50 subtype x TAM (HR ratio)0.65 (0.32-1.34); 0.240.82 (0.40-1.65); 0.57Abbreviations: BCFi, breast cancer-free interval; CI, confidence interval; ER, oestrogen receptor; HER2, human epidermal growth factor receptor 2; HR, hazard ratio; Lum, Luminal; TAM, tamoxifenAll analyses were stratified by study regiona10 years-maximum follow-up time, starting at year 10b32 and 36 years regarding BCFi and OS, respectively

Citation Format: Christine Lundgren, Pär-Ola Bendahl, Maria Ekholm, Mårten Fernö, Carina Forsare, Ute Krüger, Bo Nordenskjöld, Olle Stål, Lisa Rydén. Prognostic and tamoxifen-predictive effect of PAM50 and ROR score in premenopausal women included in the randomised SBII:2 trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD9-05.

Assessment of 25-Year Survival of Women With Estrogen Receptor-Positive/ERBB2-Negative Breast Cancer Treated With and Without Tamoxifen Therapy: A Secondary Analysis of Data From the Stockholm Tamoxifen Randomized Clinical Trial

IMPORTANCE

Clinically used breast cancer markers, such as tumor size, tumor grade, progesterone receptor (PR) status, and Ki-67 status, are known to be associated with short-term survival, but the association of these markers with long-term (25-year) survival is unclear.

OBJECTIVE

To assess the association of clinically used breast cancer markers with long-term survival and treatment benefit among postmenopausal women with lymph node-negative, estrogen receptor [ER]-positive and ERBB2-negative breast cancer who received tamoxifen therapy.

DESIGN, SETTING, AND PARTICIPANTS

This study was a secondary analysis of data from a subset of 565 women with ER-positive/ERBB2-negative breast cancer who participated in the Stockholm tamoxifen (STO-3) randomized clinical trial. The STO-3 clinical trial was conducted from 1976 to 1990 and comprised 1780 postmenopausal women with lymph node-negative breast cancer who were randomized to receive adjuvant tamoxifen therapy or no endocrine therapy. Complete 25-year follow-up data through December 31, 2016, were obtained from Swedish national registers. Immunohistochemical markers were reannotated in 2014. Data were analyzed from April to December 2020.

INTERVENTIONS

Patients in the original STO-3 clinical trial were randomized to receive 2 years of tamoxifen therapy vs no endocrine therapy. In 1983, patients who received tamoxifen therapy without cancer recurrence during the 2-year treatment and who consented to continued participation in the STO-3 study were further randomized to receive 3 additional years of tamoxifen therapy or no endocrine therapy.

MAIN OUTCOMES AND MEASURES

Distant recurrence-free interval (DRFI) by clinically used breast cancer markers was assessed using Kaplan-Meier and multivariable Cox proportional hazards analyses adjusted for age, period of primary diagnosis, tumor size (T1a and T1b [T1a/b], T1c, and T2), tumor grade (1-3), PR status (positive vs negative), Ki-67 status (low vs medium to high), and STO-3 clinical trial arm (tamoxifen treatment vs no adjuvant treatment). A recursive partitioning analysis was performed to evaluate which markers were able to best estimate long-term DRFI.

RESULTS

The study population comprised 565 postmenopausal women (mean [SD] age, 62.0 [5.3] years) with lymph node-negative, ER-positive/ERBB2-negative breast cancer. A statistically significant difference in long-term DRFI was observed by tumor size (88% for T1a/b vs 76% for T1c vs 63% for T2 tumors; log-rank P < .001) and tumor grade (81% for grade 1 vs 77% for grade 2 vs 65% for grade 3 tumors; log-rank P = .02) but not by PR status or Ki-67 status. Patients with smaller tumors (hazard ratio [HR], 0.31 [95% CI, 0.17-0.55] for T1a/b tumors and 0.58 [95% CI, 0.38-0.88] for T1c tumors) and grade 1 tumors (HR, 0.48; 95% CI, 0.24-0.95) experienced a significant reduction in the long-term risk of distant recurrence compared with patients with larger (T2) tumors and grade 3 tumors, respectively. A significant tamoxifen treatment benefit was observed among patients with larger tumors (HR, 0.53 [95% CI, 0.32-0.89] for T1c tumors and 0.34 [95% CI, 0.16-0.73] for T2 tumors), lower tumor grades (HR, 0.24 [95% CI, 0.07-0.82] for grade 1 tumors and 0.50 [95% CI, 0.31-0.80] for grade 2 tumors), and PR-positive status (HR, 0.38; 95% CI, 0.24-0.62). The recursive partitioning analysis revealed that tumor size was the most important characteristic associated with long-term survival, followed by clinical trial arm among patients with larger tumors.

CONCLUSIONS AND RELEVANCE

This secondary analysis of data from the STO-3 clinical trial indicated that, among the selected subgroup of patients, tumor size followed by tumor grade were the markers most significantly associated with long-term survival. Furthermore, a significant long-term tamoxifen treatment benefit was observed among patients with larger tumors, lower tumor grades, and PR-positive tumors.

IP6K2 predicts favorable clinical outcome of primary breast cancer

The inositol hexakisphosphate kinase (IP6K) 1 and 2 genes are localized at 3p21.31, a highly altered gene-dense chromosomal region in cancer. The IP6Ks convert IP6 to IP7, which inhibits activation of the tumor-promoting PI3K/Akt/mTOR signaling pathway. IP6K2 has been suggested to be involved in p53-induced apoptosis, while IP6K1 may stimulate tumor growth and migration. The present study aimed to elucidate the role of the two IP6Ks in predicting outcome in patients with breast cancer. To the best of our knowledge, the role of IP6K was analyzed for the first time in tumors from three cohorts of patients with breast cancer; one Swedish low-risk cohort, one Dutch cohort and the TCGA dataset. Analyses of gene -and protein expression and subcellular localization were included. IP6K2 gene expression was associated with ER positivity and nuclear p-Akt. Improved prognosis was detected with high IP6K2 gene expression compared with low IP6K2 gene expression in systemically untreated patients in the Swedish low-risk and Dutch cohorts. In the TCGA dataset, IP6K2 prognostic value was significant when selecting for tumors with wild-type TP53. A multivariable analysis testing IP6K2 against other cancer-related genes at 3p.21.31, including IP6K1 and clinical biomarkers, revealed that IP6K2 was associated with decreased risk of distant recurrence. IP6K1 was associated with increased risk of distant recurrence in the multivariable test and protein analysis revealed trends of worse prognosis with high IP6K1 in the cytoplasm. The expression levels of IP6K1 and IP6K2 were associated to a high extent; however, a diverging prognostic value of the two genes was observed in breast cancer. The present data suggest that IP6K2 can be a favorable prognostic factor, while IP6K1 may not be.

Tumor co-expression of progranulin and sortilin as a prognostic biomarker in breast cancer

Background

The growth factor progranulin has been implicated in numerous biological processes such as wound healing, inflammation and progressive tumorigenesis. Both progranulin and its receptor sortilin are known to be highly expressed in subgroups of breast cancer and have been associated with various clinical properties including tamoxifen resistance. Recent data further suggest that progranulin, via its receptor sortilin, drives breast cancer stem cell propagation in vitro and increases metastasis formation in an in vivo breast cancer xenograft model. In this retrospective biomarker analysis, we aimed to determine whether tumor co-expression of progranulin and sortilin has prognostic and treatment predictive values for breast cancer patients.

Methods

We explored how co-expression of progranulin and sortilin was associated with established clinical markers by analyzing a tissue microarray including 560 randomized premenopausal breast cancer patients receiving either 2 years of tamoxifen treatment or no adjuvant treatment, with a median follow-up time of 28 years. Breast cancer-specific survival was analyzed using Kaplan-Meier and Cox Proportional Hazards regression models to assess the prognostic and predictive value of progranulin and sortilin in relation to known clinical markers.

Results

Co-expression of progranulin and sortilin was observed in 20% of the breast cancer samples. In untreated patients, prognostic considerations could be detailed separately from treatment prediction and the high progranulin and sortilin expressing subgroup was significantly associated with breast cancer-specific death in multivariable analyses (HR=2.188, CI: 1.317–3.637, p=0.003) along with tumor size, high tumor grade and lymph node positivity. When comparing the untreated patients with tamoxifen treated patients in the ERα positive subgroup, co-expression of progranulin and sortilin was not linked to tamoxifen resistance.

Conclusion

Data suggest that co-expression of progranulin and its receptor sortilin is a novel prognostic biomarker combination identifying a highly malignant subgroup of breast cancer. Importantly, this subpopulation could potentially be targeted with anti-sortilin based therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07854-0.

Abstract PS5-09: Tumour infiltrating lymphocytes of prognostic value in different molecular breast cancer subgroups and as a suggestive predictive factor for adjuvant tamoxifen benefit in premenopausal patients after 30 years follow-up

BACKGROUND The molecular breast cancer subgroups comprise diverse immune biology; for human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC) and triple-negative breast cancer (TNBC) abundance of tumour infiltrating lymphocytes (TILs) have been shown to indicate good prognosis and could predict pathological complete response after neoadjuvant chemotherapy. In contrast, the clinical relevance of TILs in estrogen receptor-positive/HER2-negative (ER+/HER2-) tumours is not settled. We primary aimed to analyse the prognostic effect of TILs on BC-free interval (BCFi) in premenopausal patients, stratified by molecular subgroups. The secondary aim was to investigate the predictive value of TILs on tamoxifen benefit.

METHODS Archival tissue from primary tumours was collected from patients included in the SBII:2pre trial. In this study, 564 premenopausal women were randomised between two years of adjuvant tamoxifen or no systemic treatment regardless of hormone-receptor status. TILs were scored on whole tissue sections and the tumours were divided into ER+/HER2- (n = 255), HER2+ (n = 65) and TNBC (n = 95) molecular subgroups by immunohistochemistry and in situ hybridisation (ISH). The prognostic value of TILs was evaluated in patients allocated to no systemic therapy, whose tumours were successfully scored for TILs and had IHC/ISH data for generating molecular subgroups (n = 221). All patients with ER+ tumours and successfully annotated TILs were considered for prediction of tamoxifen benefit (n = 321). The median follow-up was 28 years and the prognostic and predictive analyses were performed by cumulative incidence curves and Cox regression analyses.

RESULTS TILs were successfully scored in 477 tumours with available ER status and the proportion of low (&lt;10%), intermediate (10-49%) and high (≥50%) TILs were 52% (n = 248), 33% (n = 157) and 15% (n = 72), respectively. High infiltration of TILs was a favourable prognostic factor (univariable analysis: hazard ratioBCFi (HRBCFi) 0.40; 95% confidence interval (CI) 0.22-0.71; P = 0.002) (Table 1). The results were essentially the same in the ER+/HER2- molecular subgroup (HRBCFi 0.40; 95% CI 0.14-1.09; P = 0.07). Adjuvant tamoxifen improved prognosis in patients with ER+ tumours and TILs levels &lt;50%, (univariable analysis HRBCFi 0.63; 95% CI 0.47-0.84; P = 0.002), which was not observed in patients displaying high immune infiltration (≥50%) (HRBCFi 0.84; 95% CI (0.24-2.86); P = 0.77). However, evidence for differential effect of tamoxifen in categories of TILs, i.e. interaction, was weak.

CONCLUSIONS We demonstrate a long-term favorable prognostic value of levels of TILs in a cohort of premenopausal BC patients. This effect seems to be extended to the ER+/HER2- subgroup. A beneficial effect of tamoxifen in ER+ patients was observed in patients with tumours of low TILs infiltration as compared to patients with tumours of high immune infiltration, but we could not confirm a treatment predictive effect.

Table 1. Uni- and multivariable Cox regression analyses of BCFi and OS (control arm)Univariable*MultivariableEndpointBCFiOSBCFiOSHR (95% CI); P valueTILs, category***All molecular subgroups(n = 221)(n = 213)Low (Ref.)1.001.001.001.00Intermediate1.10 (0.78-1.54); 0.611.26 (0.88-1.80); 0.210.61 (0.40-0.93); 0.020.65 (0.41-1.02); 0.06High0.40 (0.22-0.71); 0.0020.52 (0.29-0.95); 0.030.22 (0.11-0.43); &lt;0.0010.23 (0.11-0.48); &lt;0.001ER+/HER2-(n = 136)(n = 135)Low (Ref.)1.001.001.001.00Intermediate1.02 (0.63-1.64); 0.941.02 (0.61-1.71); 0.950.69 (0.42-1.15); 0.160.65 (0.37-1.15); 0.14High0.40 (0.14-1.09); 0.070.55 (0.20-1.52); 0.250.20 (0.06-0.60); 0.0040.30 (0.10-0.96); 0.04HER2+(n = 38)(n = 35)Low (Ref.)1.001.001.001.00Intermediate1.47 (0.62-3.49); 0.391.07 (0.45-2.56); 0.880.47 (0.14-1.60); 0.230.38 (0.11-1.31); 0.13High0.28 (0.08-0.97); 0.050.27 (0.08-0.96); 0.040.06 (0.01-0.56); 0.010.05 (0.01-0.39); 0.005TNBC(n = 47)(n = 43)Low (Ref.)1.001.001.001.00Intermediate0.76 (0.31-1.87); 0.551.24 (0.49-3.14); 0.650.59 (0.21-1.67); 0.321.02 (0.34-3.11); 0.97High0.27 (0.08-0.88); 0.030.44 (0.14-1.36); 0.160.38 (0.11-1.39); 0.150.59 (0.16-2.26); 0.44*Stratified by Region**The following variables were included in multivariable analysis: age (≥40 vs.&lt;40 years), nodal status (0 vs.1-3 vs. ≥4), tumour size (&gt;20 mm vs. ≤20), NHG (1 vs. 2 vs. 3), ER (positive vs. negative), PR (positive vs. negative), HER2 (positive vs. negative), LVI (present vs. absent) and TILs (high vs. intermediate vs. low). Stratified by Region.*** TILs were categorised as low: &lt;10%, intermediate: 10-49% and high: ≥50%Abbreviations: BCFi breast cancer free-interval, OS overall survival, TILs tumour infiltrating lymphocytes, HER2 human epidermal growth factor receptor 2, TNBC triple-negative breast cancer, NHG nottingham histological grade, ER estrogen receptor, PR progesterone receptor, HR hazard ratio, CI confidence interval

Citation Format: Christine Lundgren, Pär-Ola Bendahl, Maria Ekholm, Mårten Fernö, Carina Forsare, Ute Krüger, Bo Nordenskjöld, Olle Stål, Lisa Rydén. Tumour infiltrating lymphocytes of prognostic value in different molecular breast cancer subgroups and as a suggestive predictive factor for adjuvant tamoxifen benefit in premenopausal patients after 30 years follow-up [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS5-09.

MCM3 upregulation confers endocrine resistance in breast cancer and is a predictive marker of diminished tamoxifen benefit

Resistance to endocrine therapy in estrogen receptor-positive (ER+) breast cancer is a major clinical problem with poorly understood mechanisms. There is an unmet need for prognostic and predictive biomarkers to allow appropriate therapeutic targeting. We evaluated the mechanism by which minichromosome maintenance protein 3 (MCM3) influences endocrine resistance and its predictive/prognostic potential in ER+ breast cancer. We discovered that ER+ breast cancer cells survive tamoxifen and letrozole treatments through upregulation of minichromosome maintenance proteins (MCMs), including MCM3, which are key molecules in the cell cycle and DNA replication. Lowering MCM3 expression in endocrine-resistant cells restored drug sensitivity and altered phosphorylation of cell cycle regulators, including p53(Ser315,33), CHK1(Ser317), and cdc25b(Ser323), suggesting that the interaction of MCM3 with cell cycle proteins is an important mechanism of overcoming replicative stress and anti-proliferative effects of endocrine treatments. Interestingly, the MCM3 levels did not affect the efficacy of growth inhibitory by CDK4/6 inhibitors. Evaluation of MCM3 levels in primary tumors from four independent cohorts of breast cancer patients receiving adjuvant tamoxifen mono-therapy or no adjuvant treatment, including the Stockholm tamoxifen (STO-3) trial, showed MCM3 to be an independent prognostic marker adding information beyond Ki67. In addition, MCM3 was shown to be a predictive marker of response to endocrine treatment. Our study reveals a coordinated signaling network centered around MCM3 that limits response to endocrine therapy in ER+ breast cancer and identifies MCM3 as a clinically useful prognostic and predictive biomarker that allows personalized treatment of ER+ breast cancer patients.

Tumour-infiltrating lymphocytes as a prognostic and tamoxifen predictive marker in premenopausal breast cancer: data from a randomised trial with long-term follow-up

BACKGROUND

Tumour-infiltrating lymphocytes (TILs) are of important prognostic and predictive value in human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC) and triple-negative breast cancer (TNBC), but their clinical relevance in oestrogen receptor-positive/HER2-negative (ER+/HER2-) remains unknown. The primary study aim was to analyse the prognostic effect of TILs on the BC-free interval (BCFi) in premenopausal patients stratified by BC subtypes. The secondary aim was to investigate if TILs are predictive of tamoxifen (TAM) benefit.

METHODS

Archival tissues from primary breast tumours were collected from patients from the SBII:2pre trial, in which 564 premenopausal women were randomised to 2 years of adjuvant TAM or no systemic treatment, regardless of hormone receptor status. TILs were scored on whole tissue sections from 447 patients with available ER status. Tumours were divided into ER+/HER2-, HER2+ and TNBC subtypes by immunohistochemistry and in situ hybridisation. The prognostic value of TILs was analysed in systemically untreated patients (n = 221); the predictive information was investigated in the ER+ subgroup (n = 321) by cumulative incidence curves and Cox regression analyses. The median follow-up was 28 years.

RESULTS

High (≥ 50%) infiltration of TILs was a favourable prognostic factor in terms of BCFi (univariable analysis: hazard ratioBCFi (HRBCFi) 0.40; 95% confidence interval (CI) 0.22-0.71; P = 0.002). Similar effects were observed across all BC subtypes. The effect of adjuvant TAM was stronger in patients with ER+ tumours and TILs < 50% (HRBCFi 0.63; 95% CI 0.47-0.84; P = 0.002) than in patients with high immune infiltration (≥ 50%) (HRBCFi 0.84; 95% CI (0.24-2.86); P = 0.77). However, evidence for differential effects of TAM in categories of TILs, i.e. interaction, was weak.

CONCLUSIONS

We demonstrate a long-term favourable prognostic value of high infiltration of TILs in a cohort of premenopausal BC patients and the positive prognostic effect was extended to the ER+/HER2- subgroup. A beneficial effect of TAM in ER+ patients was observed in patients with tumours of low TIL infiltration, but evidence for a treatment predictive effect was weak.

TRIAL REGISTRATION

This trial is registered in the ISRCTN database, trial ID: ISRCTN12474687 .

Expression of HGF, pMet, and pAkt is related to benefit of radiotherapy after breast-conserving surgery: a long-term follow-up of the SweBCG91-RT randomised trial

Experimental studies suggest that hepatocyte growth factor (HGF) and its transmembrane tyrosine kinase receptor, Met, in part also relying on Akt kinase activity, mediate radioresistance. We investigated the importance of these biomarkers for the risk of ipsilateral breast tumour recurrence (IBTR) after adjuvant radiotherapy (RT) in primary breast cancer. HGF, phosphorylated Met (pMet) and phosphorylated Akt (pAkt) were evaluated immunohistochemically on tissue microarrays from 1004 patients in the SweBCG91‐RT trial, which randomly assigned patients to breast‐conserving therapy, with or without adjuvant RT. HGF was evaluated in the stroma (HGF_str); pMet in the membrane (pMet_mem); HGF, pMet and pAkt in the cytoplasm (HGF_cyt, pMet_cyt, pAkt_cyt); and pAkt in the nucleus (pAkt_nuc). The prognostic and treatment predictive effects were evaluated to primary endpoint IBTR as first event during the first 5 years. Patients with tumours expressing low levels of HGF_cyt and pMet_cyt and high levels of pAkt_nuc derived a larger benefit from RT [hazard ratio (HR): 0.11 (0.037–0.30), 0.066 (0.016–0.28) and 0.094 (0.028–0.31), respectively] compared to patients with high expression of HGF_cyt and pMet_cyt, and low pAkt_nuc [HR: 0.36 (0.19–0.67), 0.35 (0.20–0.64) and 0.47 (0.32–0.71), respectively; interaction analyses: P = 0.052, 0.035 and 0.013, respectively]. These differences remained in multivariable analysis when adjusting for patient age, tumour size, histological grade, St Gallen subtype and systemic treatment (interaction analysis, P‐values: 0.085, 0.027, and 0.023, respectively). This study suggests that patients with immunohistochemically low HGF_cyt, low pMet_cyt and high pAkt_nuc may derive an increased benefit from RT after breast‐conserving surgery concerning the risk of developing IBTR.

Low RAB6C expression is a predictor of tamoxifen benefit in estrogen receptor-positive/progesterone receptor-negative breast cancer

Over the last few decades, improved and more individualized treatment has contributed to the increased survival rate of patients with breast cancer. However, certain patients may receive excessive treatment resulting in undesired side effects. In a previous study, it was demonstrated that systemically untreated patients with estrogen receptor (ER)-positive/progesterone receptor (PR)-negative tumors with high Ras-related protein Rab-6C (RAB6C) expression levels (RAB6C⁺) had prolonged distant recurrence-free survival compared with that of patients exhibiting low RAB6C (RAB6C^-)-expressing tumors. The aim of the present study was to investigate whether RAB6C predicts the effectiveness of tamoxifen treatment. The present study used a dataset comprising 486 female patients with ER⁺ tumors from a randomized study conducted by the Stockholm Breast Cancer Study Group between November 1976 and August 1990. The patients were considered as low-risk if their tumor size was ≤30 mm and their lymph node status was negative. Patients were followed up until distant recurrence, mortality or when 25 years after randomization was achieved, whichever occurred first. For patients with ER⁺/PR^-/RAB6C⁺ tumors, prolonged distant recurrence-free survival could not be observed if the patients were treated with tamoxifen [hazard ratio (HR), 1.82; 95% confidence interval (CI), 0.69-4.79; P=0.23], whereas patients with ER⁺/PR^-/RAB6C^- tumors had 75% reduced distant recurrence risk (HR, 0.25; 95% CI, 0.09-0.70; P=0.008). In the ER⁺/PR⁺ subgroup, patients with RAB6C^- and RAB6C⁺ tumors benefited from tamoxifen treatment, though it was most evident in the RAB6C⁺ group (HR, 0.27; 95% CI, 0.13-0.58; P=0.001). The results of the present study indicated that, for patients with ER⁺/PR^- tumors, those with low RAB6C expression benefited from tamoxifen treatment, whereas no benefit was observed in patients with high RAB6C levels.

RAB6C is an independent prognostic factor of estrogen receptor-positive/progesterone receptor-negative breast cancer

The majority of breast cancer tumors are estrogen receptor-positive (ER⁺) and can be treated with endocrine therapy. However, certain patients may exhibit a good prognosis without systemic treatment. The aim of the present study was to identify novel prognostic factors for patients with ER⁺ breast cancer tumors using gene copy data, and to investigate if these factors have prognostic value in subgroups categorized by progesterone receptor status (PR). Public data, including the whole genome gene copy data of 199 systemically untreated patients with ER⁺ tumors, were utilized in the present study. To assess prognostic value, patients were divided into two groups using the median gene copy number as a cut-off for the SNPs that were the most variable. One SNP was identified, which indicated that the Ras-related protein Rab-6C (RAB6C) gene may exhibit prognostic significance. Therefore, RAB6C protein expression was subsequently investigated in a second independent cohort, consisting of 469 systematically untreated patients (of which 310 were ER⁺) who received long term follow-up. In the public data set, a distant recurrence risk reduction of 55% was determined for copy numbers above the median value of RAB6C compared with numbers below [multivariable adjusted hazard ratio (HR), 0.45; 95% CI 0.28–0.72; P=0.001)]. It was also more pronounced in the ER⁺/PR⁻ subgroup (HR, 0.15; 95% CI, 0.05–0.46; P=0.001). In the second cohort, patients of the ER⁺/PR⁻ subgroup who exhibited high RAB6C expression had a reduced distant recurrence risk (HR, 0.17; 95% CI, 0.05–0.60; P=0.006). However, this was not identified among ER⁺/PR⁺ tumors (HR, 1.31; 95% CI, 0.69–2.48; P=0.41). The results of the present study indicated that RAB6C serves as an independent prognostic factor of distant recurrence risk in systemically untreated patients with an ER⁺/PR⁻ tumor.

Assessment of Long-term Distant Recurrence-Free Survival Associated With Tamoxifen Therapy in Postmenopausal Patients With Luminal A or Luminal B Breast Cancer

Importance

Patients with estrogen receptor (ER)-positive breast cancer have a long-term risk for fatal disease. However, the tumor biological factors that influence the long-term risk and the benefit associated with endocrine therapy are not well understood.

Objective

To compare the long-term survival from tamoxifen therapy for patients with luminal A or luminal B tumor subtype.

Design, Setting, and Participants

Secondary analysis of patients from the Stockholm Tamoxifen (STO-3) trial conducted from 1976 to 1990, which randomized postmenopausal patients with lymph node-negative breast cancer to receive adjuvant tamoxifen or no endocrine therapy. Tumor tissue sections were assessed in 2014 using immunohistochemistry and Agilent microarrays. Only patients with luminal A or B subtype tumors were evaluated. Complete long-term follow-up data up to the end of the STO-3 trial on December 31, 2012, were obtained from the Swedish National registers. Data analysis for the secondary analysis was conducted in 2017 and 2018.

Interventions

Patients were randomized to receive at least 2 years of tamoxifen therapy or no endocrine therapy; patients without recurrence who reconsented were further randomized to 3 additional years of tamoxifen therapy or no endocrine therapy.

Main Outcomes and Measures

Distant recurrence-free interval (DRFI) by luminal A and luminal B subtype and trial arm was assessed by Kaplan-Meier analyses and time-dependent flexible parametric models to estimate time-varying hazard ratios (HRs) that were adjusted for patient and tumor characteristics.

Results

In the STO-3 treated trial arm, 183 patients had luminal A tumors and 64 patients had luminal B tumors. In the untreated arm, 153 patients had luminal A tumors and 62 had luminal B tumors. Age at diagnosis ranged from 45 to 73 years. A statistically significant difference in DRFI by trial arm was observed (log rank, P < .001 [luminal A subtype, n = 336], P = .04 [luminal B subtype, n = 126]): the 25-year DRFI for luminal A vs luminal B subtypes was 87% (95% CI, 82%-93%) vs 67% (95% CI, 56%-82%) for treated patients, and 70% (95% CI, 62%-79%) vs 54% (95% CI, 42%-70%) for untreated patients, respectively. Patients with luminal A tumors significantly benefited from tamoxifen therapy for 15 years after diagnosis (HR, 0.57; 95% CI, 0.35-0.94), and those with luminal B tumors benefited from tamoxifen therapy for 5 years (HR, 0.38; 95% CI, 0.24-0.59).

Conclusions and Relevance

Patients with luminal A subtype tumors had a long-term risk of distant metastatic disease, which was reduced by tamoxifen treatment, whereas patients with luminal B tumors had an early risk of distant metastatic disease, and tamoxifen benefit attenuated over time.

Intratumor Heterogeneity of the Estrogen Receptor and the Long-term Risk of Fatal Breast Cancer

Background

Breast cancer patients with estrogen receptor (ER)–positive disease have a continuous long-term risk for fatal breast cancer, but the biological factors influencing this risk are unknown. We aimed to determine whether high intratumor heterogeneity of ER predicts an increased long-term risk (25 years) of fatal breast cancer.

Methods

The STO-3 trial enrolled 1780 postmenopausal lymph node–negative breast cancer patients randomly assigned to receive adjuvant tamoxifen vs not. The fraction of cancer cells for each ER intensity level was scored by breast cancer pathologists, and intratumor heterogeneity of ER was calculated using Rao’s quadratic entropy and categorized into high and low heterogeneity using a predefined cutoff at the second tertile (67%). Long-term breast cancer-specific survival analyses by intra-tumor heterogeneity of ER were performed using Kaplan-Meier and multivariable Cox proportional hazard modeling adjusting for patient and tumor characteristics.

Results

A statistically significant difference in long-term survival by high vs low intratumor heterogeneity of ER was seen for all ER-positive patients (P < .001) and for patients with luminal A subtype tumors (P = .01). In multivariable analyses, patients with high intratumor heterogeneity of ER had a twofold increased long-term risk as compared with patients with low intratumor heterogeneity (ER-positive: hazard ratio [HR] = 1.98, 95% confidence interval [CI] = 1.31 to 3.00; luminal A subtype tumors: HR = 2.43, 95% CI = 1.18 to 4.99).

Conclusions

Patients with high intratumor heterogeneity of ER had an increased long-term risk of fatal breast cancer. Interestingly, a similar long-term risk increase was seen in patients with luminal A subtype tumors. Our findings suggest that intratumor heterogeneity of ER is an independent long-term prognosticator with potential to change clinical management, especially for patients with luminal A tumors.

The effects of PTPN2 loss on cell signalling and clinical outcome in relation to breast cancer subtype

Purpose

The protein tyrosine phosphatase PTPN2 dephosphorylates several tyrosine kinases in cancer-related signalling pathways and is thought to be a tumour suppressor. As PTPN2 is not frequently studied in breast cancer, we aimed to explore the role of PTPN2 and the effects of its loss in breast cancer.

Methods

Protein expression and gene copy number of PTPN2 were analysed in a cohort of pre-menopausal breast cancer patients with immunohistochemistry and droplet digital PCR, respectively. PTPN2 was knocked down in three cell lines, representing different breast cancer subtypes, with siRNA transfection. Several proteins related to PTPN2 were analysed with Western blot.

Results

Low PTPN2 protein expression was found in 50.2% of the tumours (110/219), gene copy loss in 15.4% (33/214). Low protein expression was associated with a higher relapse rate in patients with Luminal A and HER2-positive tumours, but not triple-negative tumours. In vitro studies further suggested a subtype-specific role of PTPN2. Knockdown of PTPN2 had no effect on the triple-negative cell line, whilst knockdown in MCF7 inhibited phosphorylation of Met and promoted that of Akt. Knockdown in SKBR3 led to increased Met phosphorylation and decreased Erk phosphorylation as well as EGF-mediated STAT3 activation.

Conclusion

We confirm previous studies showing that the PTPN2 protein is lost in half of the breast cancer cases and gene deletion occurs in 15–18% of the cases. Furthermore, the results suggest that the role of PTPN2 is subtype-related and should be further investigated to assess how this could affect breast cancer prognosis and treatment response.

Abstract P2-13-06: Long term clinical follow up of real world HER2-positive patients since the introduction of trastuzumab

Background: The prognosis for patients with HER2-positive early breast cancer (EBC) has improved dramatically since the introduction of adjuvant trastuzumab therapy. With the addition of pertuzumab the prognosis has improved further. However, there is a need to study how these results from clinical controlled trials are transferred to the real-world clinical setting. In this study we aim to investigate all patients with early HER2-positive breast cancer in our region since the introduction of adjuvant trastuzumab to evaluate the implementation of trastuzumab treatment regarding treatment coverage, prognosis and survival.

Method: All patients with HER2-positve EBC, diagnosed between 2006 and 2014 in South-east Sweden were included in the study. The patients were identified using the Swedish national breast cancer register and then cross-referenced with data from the pathology department at each hospital in order to obtain complete coverage in a retrospective clinical follow up. In addition, data were collected from medical records for each patient to verify the actual given treatments and survival data.

Results: Preliminary data is available. 611 patients were included with a median follow-up time of 5 years. During the follow-up period the number of patients diagnosed with HER2-positive EBC cancer doubled. 73% of all patients received trastuzumab treatment; however the coverage increased successively from 56% in 2006 to 83% in 2013. ER-positive patients did receive trastuzumab therapy to the same extent as ER-negative patients. Local recurrence-free survival (LRFS), distant recurrence-free survival (DRFS) and breast cancer specific survival (BCSS) at 5 years were 85%, 76%, and 75% for patients not receiving trastuzumab. In the trastuzumab treated group LRFS, DRFS and BCSS was 95%, 85% and 83% respectively. The group not receiving trastuzumab was significantly older, had more frequently node negative disease and was not treated with chemotherapy to the same extent.

Conclusion: A significant amount of early HER2-positive breast cancer patients did not receive adjuvant trastuzumab therapy between 2006 and 2014. In this group fewer patients received chemotherapy and despite less nodal involvement LRFS, DRFS and BCSS were poor for these patients.

Citation Format: Ellegard S, Asowed M, Engvall K, Hallbeck A-L, Elander N, Stål O. Long term clinical follow up of real world HER2-positive patients since the introduction of trastuzumab [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-13-06.

Abstract P4-14-10: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Ekholm M, Bendahl P-O, Fernö M, Nordenskjöld B, Stål O, Rydén L. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-14-10.

Effects of adjuvant tamoxifen over three decades on breast cancer-free and distant recurrence-free interval among premenopausal women with oestrogen receptor-positive breast cancer randomised in the Swedish SBII:2pre trial

AIMS

The primary aim was to compare 2 years of adjuvant tamoxifen versus no systemic treatment in premenopausal patients with oestrogen receptor (ER)-positive tumours, regarding breast cancer-free interval (BCFi) and distant recurrence-free interval (D-RFi), with 30 years of follow-up and for specified intervals. Moreover, we aimed to investigate the effects of adjuvant tamoxifen on the incidence of secondary malignancies and survival after distant recurrence.

METHODS

Premenopausal patients with primary breast cancer were randomised to 2 years of tamoxifen (n = 277) or no systemic treatment (n = 287), irrespective of ER status. Information regarding events was collected by a review of medical records and from national registers.

RESULTS

The median follow-up for all patients without events was 28 years, and only four of the patients alive had a follow-up of <20 years. With 30 years of follow-up, tamoxifen prolonged BCFi in the intention-to-treat population (hazard ratio [HR] = 0.76, 95% confidence interval (CI) 0.61-0.94, p = 0.011) compared with no treatment. In patients with ER-positive tumours (n = 362), tamoxifen prolonged BCFi (HR = 0.62, 95% CI 0.47-0.82, p = 0.001) and D-RFi (HR = 0.73, 95% CI 0.54-0.99, p = 0.043). The positive effect on BCFi was significant also for the interval >15-30 years (HR = 0.53, 95% CI 0.28-0.98, p = 0.042). For patients with ER-positive tumours who were diagnosed with distant recurrence (n = 165), survival after distant recurrence was shorter among tamoxifen-treated patients (median, 29 months versus 43 months). The incidence of contralateral breast cancer was 42% lower in the tamoxifen group (HR = 0.58, 95% CI 0.35-0.96, p = 0.035), whereas no differences were observed regarding other secondary malignancies.

CONCLUSIONS

With three decades of follow-up, 2 years of adjuvant tamoxifen reduced the incidence of breast cancer-related events and distant recurrence, and the carryover effect seems to extend beyond 15 years. Moreover, adjuvant tamoxifen seems to be associated with shorter survival after diagnosis of distant recurrence.

ERBB2 and PTPN2 gene copy numbers as prognostic factors in HER2-positive metastatic breast cancer treated with trastuzumab

Trastuzumab has markedly improved the treatment and long-term prognosis of patients with HER2-positive breast cancer. A frequent clinical challenge in patients with relapsing and/or metastatic disease is de novo or acquired trastuzumab resistance, and to date no predictive biomarkers for palliative trastuzumab have been established. In the present study, the prognostic values of factors involved in the HER2-associated PI3K/Akt signalling pathway were explored. The first 46 consecutive patients treated at the Department of Oncology, Linköping University Hospital between 2000 and 2007 with trastuzumab for HER2-positive metastatic breast cancer were retrospectively included. The gene copy number variation and protein expression of several components of the PI3K/Akt pathway were assessed in the tumour tissue and biopsy samples using droplet digital polymerase chain reaction and immunohistochemistry. Patients with tumours displaying a high-grade ERBB2 (HER2) amplification level of ≥6 copies had a significantly improved overall survival hazard ratio [(HR)=0.4; 95%, confidence interval (CI): 0.2–0.9] and progression-free survival (HR=0.3; 95% CI: 0.1–0.7) compared with patients with tumours harbouring fewer ERBB2 copies. High-grade ERBB2 amplification was significantly associated with the development of central nervous system metastases during palliative treatment. Copy gain (≥3 copies) of the gene encoding the tyrosine phosphatase PTPN2 was associated with a shorter overall survival (HR=2.0; 95% CI: 1.0–4.0) and shorter progression-free survival (HR=2.1; 95% CI: 1.0–4.1). In conclusion, high ERBB2 amplification level is a potential positive prognostic factor in trastuzumab-treated HER2-positive metastatic breast cancer, whereas PTPN2 gain is a potential negative prognostic factor. Further studies are warranted on the role of PTPN2 in HER2 signalling.

Non-linear transformations of age at diagnosis, tumor size, and number of positive lymph nodes in prediction of clinical outcome in breast cancer

BACKGROUND

Prognostic factors in breast cancer are often measured on a continuous scale, but categorized for clinical decision-making. The primary aim of this study was to evaluate if accounting for continuous non-linear effects of the three factors age at diagnosis, tumor size, and number of positive lymph nodes improves prognostication. These factors will most likely be included in the management of breast cancer patients also in the future, after an expected implementation of gene expression profiling for adjuvant treatment decision-making.

METHODS

Four thousand four hundred forty seven and 1132 women with primary breast cancer constituted the derivation and validation set, respectively. Potential non-linear effects on the log hazard of distant recurrences of the three factors were evaluated during 10 years of follow-up. Cox-models of successively increasing complexity: dichotomized predictors, predictors categorized into three or four groups, and predictors transformed using fractional polynomials (FPs) or restricted cubic splines (RCS), were used. Predictive performance was evaluated by Harrell's C-index.

RESULTS

Using FP-transformations, non-linear effects were detected for tumor size and number of positive lymph nodes in univariable analyses. For age, non-linear transformations did, however, not improve the model fit significantly compared to the linear identity transformation. As expected, the C-index increased with increasing model complexity for multivariable models including the three factors. By allowing more than one cut-point per factor, the C-index increased from 0.628 to 0.674. The additional gain, as measured by the C-index, when using FP- or RCS-transformations was modest (0.695 and 0.696, respectively). The corresponding C-indices for these four models in the validation set, based on the same transformations and parameter estimates from the derivation set, were 0.675, 0.700, 0.706, and 0.701.

CONCLUSIONS

Categorization of each factor into three to four groups was found to improve prognostication compared to dichotomization. The additional gain by allowing continuous non-linear effects modeled by FPs or RCS was modest. However, the continuous nature of these transformations has the advantage of making it possible to form risk groups of any size.

PTPN2 deficiency along with activation of nuclear Akt predict endocrine resistance in breast cancer

Purpose

The protein tyrosine phosphatase, non-receptor type 2 (PTNP2) regulates receptor tyrosine kinase signalling, preventing downstream activation of intracellular pathways like the PI3K/Akt pathway. The gene encoding the protein is located on chromosome 18p11; the 18p region is commonly deleted in breast cancer. In this study, we aimed to evaluate PTPN2 protein expression in a large breast cancer cohort, its possible associations to PTPN2 gene copy loss, Akt activation, and the potential use as a clinical marker in breast cancer.

Methods

PTPN2 protein expression was analysed by immunohistochemistry in 664 node-negative breast tumours from patients enrolled in a randomised tamoxifen trial. DNA was available for 146 patients, PTPN2 gene copy number was determined by real-time PCR.

Results

PTPN2 gene loss was detected in 17.8% of the tumours. Low PTPN2 protein expression was associated with higher levels of nuclear-activated Akt (pAkt-n). Low PTPN2 as well as the combination variable low PTPN2/high pAkt-n could be used as predictive markers of poor tamoxifen response.

Conclusion

PTPN2 negatively regulates Akt signalling and loss of PTPN2 protein along with increased pAkt-n is a new potential clinical marker of endocrine treatment efficacy, which may allow for further tailored patient therapies.

Apoptosis and Bcl-2 Expression in Relation to Age, Tumor Characteristics and Prognosis in Breast Cancer

The extent of apoptosis and the expression of Bcl-2 was investigated in tumor samples from 165 women who underwent surgery for primary breast carcinoma between 1989 and 1990 in South-East Sweden. Apoptosis was assessed by a DNA fragmentation assay for flow cytometry. Bcl-2 protein expression was analyzed with immunocytochemistry Bcl-2 immunoreactivity correlated with estrogen receptor (ER) and progesterone receptor (PgR) positivity and was inversely correlated with p53 accumulation. Apoptosis increased with patient age and a high degree of apoptosis was negatively associated with Bcl-2 immunostaining. Apoptosis showed no significant correlation with any of the other variables studied, including prognosis. The group with Bcl-2-positive tumors tended to have a lower risk of distant recurrence than others, but the association of Bcl-2 with recurrence was different in groups divided by ER and PgR status. Whereas Bcl-2 positivity indicated a low recurrence rate among PgR-negative patients, in the PgR-positive group, those with Bcl-2-positive tumors showed a non significantly higher recurrence rate than Bcl-2-negative cases. In the PgR-positive group, Bcl-2-positive tumors also appeared more frequently to be lymph node positive and DNA aneuploid. The results suggest that hormone receptor status is of importance for the prognostic role of Bcl-2. Likewise, patient age merits consideration when apoptosis is studied in human cancer.

Estrogen and androgen-converting enzymes 17β-hydroxysteroid dehydrogenase and their involvement in cancer: with a special focus on 17β-hydroxysteroid dehydrogenase type 1, 2, and breast cancer

Sex steroid hormones such as estrogens and androgens are involved in the development and differentiation of the breast tissue. The activity and concentration of sex steroids is determined by the availability from the circulation, and on local conversion. This conversion is primarily mediated by aromatase, steroid sulfatase, and 17β-hydroxysteroid dehydrogenases. In postmenopausal women, this is the primary source of estrogens in the breast. Up to 70-80% of all breast cancers express the estrogen receptor-α, responsible for promoting the growth of the tissue. Further, 60-80% express the androgen receptor, which has been shown to have tissue protective effects in estrogen receptor positive breast cancer, and a more ambiguous response in estrogen receptor negative breast cancers. In this review, we summarize the function and clinical relevance in cancer for 17β-hydroxysteroid dehydrogenases 1, which facilitates the reduction of estrone to estradiol, dehydroepiandrosterone to androstendiol and dihydrotestosterone to 3α- and 3β-diol as well as 17β-hydroxysteroid dehydrogenases 2 which mediates the oxidation of estradiol to estrone, testosterone to androstenedione and androstendiol to dehydroepiandrosterone. The expression of 17β-hydroxysteroid dehydrogenases 1 and 2 alone and in combination has been shown to predict patient outcome, and inhibition of 17β-hydroxysteroid dehydrogenases 1 has been proposed to be a prime candidate for inhibition in patients who develop aromatase inhibitor resistance or in combination with aromatase inhibitors as a first line treatment. Here we review the status of inhibitors against 17β-hydroxysteroid dehydrogenases 1. In addition, we review the involvement of 17β-hydroxysteroid dehydrogenases 4, 5, 7, and 14 in breast cancer.

Met and its ligand HGF are associated with clinical outcome in breast cancer

Few biomarkers exist to predict radiotherapy response in breast cancer. In vitro studies suggest a role for Met and its ligand HGF. To study this suggested role, MET and HGF gene copy numbers were determined by droplet digital PCR in tumours from 205 pre-menopausal and 184 post-menopausal patients, both cohorts randomised to receive either chemo- or radiotherapy. MET amplification was found in 8% of the patients in both cohorts and HGF amplification in 7% and 6% of the patients in the pre- and post-menopausal cohort, respectively. Met, phosphorylated Met (pMet), and HGF protein expression was determined by immunohistochemistry in the pre-menopausal cohort. Met, pMet, and HGF was expressed in 33%, 53%, and 49% of the tumours, respectively. MET amplification was associated with increased risk of distant recurrence for patients receiving chemotherapy. For the pre-menopausal patients, expression of cytoplasmic pMet and HGF significantly predicted benefit from radiotherapy in terms of loco-regional recurrence. Similar trends were seen for MET and HGF copy gain. In the post-menopausal cohort, no significant association of benefit from radiotherapy with neither genes nor proteins was found. The present results do not support that inhibition of Met prior to radiotherapy would be favourable for pre-menopausal breast cancer, as previously suggested.

Use of Molecular Tools to Identify Patients With Indolent Breast Cancers With Ultralow Risk Over 2 Decades

Importance

The frequency of cancers with indolent behavior has increased with screening. Better tools to identify indolent tumors are needed to avoid overtreatment.

Objective

To determine if a multigene classifier is associated with indolent behavior of invasive breast cancers in women followed for 2 decades.

Design, Setting, and Participants

This is a secondary analysis of a randomized clinical trial of tamoxifen vs no systemic therapy, with more than 20-year follow-up. An indolent threshold (ultralow risk) of the US Food and Drug Administration-cleared MammaPrint 70-gene expression score was established above which no breast cancer deaths occurred after 15 years in the absence of systemic therapy. Immunohistochemical markers (n = 727 women) and Agilent microarrays, for MammaPrint risk scoring (n = 652 women), were performed from formalin-fixed paraffin-embedded primary tumor blocks. Participants were postmenopausal women with clinically detected node-negative breast cancers treated with mastectomy or lumpectomy and radiation enrolled in the Stockholm tamoxifen (STO-3) trial, 1976 to 1990.

Exposures

After 2 years of tamoxifen vs no systemic therapy, regardless of hormone receptor status, patients without relapse who reconsented were further randomized to 3 additional years or none.

Main Outcomes and Measures

Breast cancer-specific survival assessed by Kaplan-Meier analyses and multivariate Cox proportional hazard modeling, adjusted for treatment, patient age, year of diagnosis, tumor size, grade, hormone receptors, and ERBB2/HER2 and Ki67 status.

Results

In this secondary analysis of node-negative postmenopausal women, conducted in the era before mammography screening, among the 652 women with MammaPrint scoring available (median age, 62.8 years of age), 377 (58%) and 275 (42%) were MammaPrint low and high risk, respectively, while 98 (15%) were ultralow risk. At 20 years, women with 70-gene high and low tumors but not ultralow tumors had a significantly higher risk of disease-specific death compared with ultralow-risk patients by Cox analysis (hazard ratios, 4.73 [95% CI, 1.38-16.22] and 4.54 [95% CI, 1.40-14.80], respectively). There were no deaths in the ultralow-risk tamoxifen-treated arm at 15 years, and these patients had a 20-year disease-specific survival rate of 97%, whereas for untreated patients the survival rate was 94%. Recursive partitioning identified ultralow risk as the most significant predictor of good outcome. In tumors "not ultralow risk," tumor size greater than 2 cm was the most predictive of outcome.

Conclusions and Relevance

The ultralow-risk threshold of the 70-gene MammaPrint assay can identify patients whose long-term systemic risk of death from breast cancer after surgery alone is exceedingly low.

Raptor localization predicts prognosis and tamoxifen response in estrogen receptor-positive breast cancer

Purpose

Deregulated PI3K/mTOR signals can promote the growth of breast cancer and contribute to endocrine treatment resistance. This report aims to investigate raptor and its intracellular localization to further understand its role in ER-positive breast cancer.

Methods

Raptor protein expression was evaluated by immunohistochemistry in 756 primary breast tumors from postmenopausal patients randomized to tamoxifen or no tamoxifen. In vitro, the MCF7 breast cancer cell line and tamoxifen-resistant MCF7 cells were studied to track the raptor signaling changes upon resistance, and raptor localization in ERα-positive cell lines was compared with that in ERα-negative cell lines.

Results

Raptor protein expression in the nucleus was high in ER/PgR-positive and HER2-negative tumors with low grade, features associated with the luminal A subtype. Presence of raptor in the nucleus was connected with ERα signaling, here shown by a coupled increase of ERα phosphorylation at S167 and S305 with accumulation of nuclear raptor. In addition, the expression of ERα-activated gene products correlated with nuclear raptor. Similarly, in vitro we observed raptor in the nucleus of ERα-positive, but not of ER-negative cells. Interestingly, raptor localized to the nucleus could still be seen in tamoxifen-resistant MCF7 cells. The clinical benefit from tamoxifen was inversely associated with an increase of nuclear raptor. High cytoplasmic raptor expression indicated worse prognosis on long-term follow-up.

Conclusion

We present a connection between raptor localization to the nucleus and ERα-positive breast cancer, suggesting raptor as a player in stimulating the growth of the luminal A subtype and a possible target along with endocrine treatment.

Electronic supplementary material

The online version of this article (10.1007/s10549-017-4508-x) contains supplementary material, which is available to authorized users.

Tamoxifen therapy benefit for patients with 70-gene signature high and low risk

Background

Breast cancer molecular prognostic tools that predict recurrence risk have mainly been established on endocrine-treated patients and thus are not optimal for the evaluation of benefit from endocrine therapy. The Stockholm tamoxifen (STO-3) trial which randomized postmenopausal node-negative patients to 2-year tamoxifen (followed by an optional randomization for an additional 3-year tamoxifen vs nil), versus no adjuvant treatment, provides a unique opportunity to evaluate long-term 20-year benefit of endocrine therapy within prognostic risk classes of the 70-gene prognosis signature that was developed on adjuvantly untreated patients.

Methods

We assessed by Kaplan–Meier analysis 20-year breast cancer-specific survival (BCSS) and 10-year distant metastasis-free survival (DMFS) for 538 estrogen receptor (ER)-positive, STO-3 trial patients with retrospectively ascertained 70-gene prognosis classification. Multivariable analysis of long-term (20 years) BCSS by STO-3 trial arm in the 70-gene high-risk and low-risk subgroups was performed using Cox proportional hazard modeling adjusting for classical patient and tumor characteristics.

Results

Tamoxifen-treated, 70-gene low- and high-risk patients had 20-year BCSS of 90 and 83%, as compared to 80 and 65% for untreated patients, respectively (log-rank p < 0.0001). Notably, there is equivalent tamoxifen benefit in both high (HR 0.42 (0.21–0.86), p = 0.018) and low (HR 0.46 (0.25–0.85), p = 0.013) 70-gene risk categories even after adjusting for clinico-pathological factors for BCSS. Limited tamoxifen exposure as given in the STO-3 trial provides persistent benefit for 10–15 years after diagnosis in a time-varying analysis. 10-year DMFS was 93 and 85% for low- and high-risk tamoxifen-treated, versus 83 and 70% for low- and high-risk untreated patients, respectively (log-rank p < 0.0001).

Conclusions

Patients with ER-positive breast cancer, regardless of high or low 70-gene risk classification, receive significant survival benefit lasting over 10 years from adjuvant tamoxifen therapy, even when given for a relatively short duration.

Electronic supplementary material

The online version of this article (doi:10.1007/s10549-017-4428-9) contains supplementary material, which is available to authorized users.

The regulation of hydroxysteroid 17β-dehydrogenase type 1 and 2 gene expression in breast cancer cell lines by estradiol, dihydrotestosterone, microRNAs, and genes related to breast cancer

AIM

To investigate the influence of estrogen, androgen, microRNAs, and genes implicated in breast cancer on the expression of HSD17B1 and HSD17B2.

MATERIALS

Breast cancer cell lines ZR-75-1, MCF7, T47D, SK-BR-3, and the immortalized epithelial cell line MCF10A were used. Cells were treated either with estradiol or dihydrotestosterone for 6, 24, 48 hours, or 7 days or treated with miRNAs or siRNAs predicted to influence HSD17B expression Results and discussion. Estradiol treatment decreased HSD17B1 expression and had a time-dependent effect on HSD17B2 expression. This effect was lost in estrogen receptor-α down-regulated or negative cell lines. Dihydrotestosterone treatment increased HSD17B2 expression, with limited effect on HSD17B1 expression. No effect was seen in cells without AR or in combination with the AR inhibitor hydroxyflutamide. The miRNA-17 up-regulated HSD17B1, while miRNA-210 and miRNA-7-5p had up- and down-regulatory effect and miRNA-1304-3p reduced HSD17B1 expression. The miRNA-204-5p, 498, 205-3p and 579-3p reduced HSD17B2 expression. Downregulation of CX3CL1, EPHB6, and TP63 increased HSD17B1 and HSD17B2 expression, while GREB1 downregulation suppressed HSD17B1 and promoted HSD17B2 expression.

CONCLUSION

We show that HSD17B1 and HSD17B2 are controlled by estradiol, dihydrotestosterone, and miRNAs, as well as modulated by several breast cancer-related genes, which could have future clinical applications.

Long-term effects on the incidence of second primary cancers in a randomized trial of two and five years of adjuvant tamoxifen

BACKGROUND

Tamoxifen is a well established treatment for breast cancer, but its long-term effects on the incidence of secondary cancers are not fully evaluated.

MATERIAL AND METHODS

We have studied 4128 postmenopausal patients with early stage breast cancer who were alive and free of breast cancer recurrence after two years of tamoxifen, and who were randomized to receive totally two or five years of therapy.

RESULTS

Compared to patients randomized to two years of tamoxifen the incidence of contralateral breast cancer [hazard ratio (HR) 0.73; 95% CI 0.56-0.96] and of lung cancer (HR 0.45; 95% CI 0.27-0.77), especially squamous cell and small cell lung cancer, were reduced in the five-year group, and similar results were seen when restricting the analysis to the 10-year period after treatment stopped. An increased incidence of endometrial cancer was observed in the five-year group, but the excess risk decreased over time.

CONCLUSION

Further studies of the effects of tamoxifen on the risk of different histological types of lung cancer are needed.

Abstract PD7-02: Identification of breast cancers with an indolent disease course: 70 gene indolent threshold validation in a Swedish randomized trial of tamoxifen vs. not, with 20 year outcomes

Importance: The frequency of cancers with indolent behavior has increased with screening. We asked whether an ultralow risk threshold on a multigene classifier would identify women whose cancers had an indolent course over 2 decades of follow-up, and which features were most predictive of outcome.

Methods: An ultralow risk threshold of the FDA-cleared MammaPrint 70-gene expression score was set to predict long-term absence of breast cancer-specific mortality in the absence of systemic therapy. The Stockholm Tamoxifen (STO) trial conducted between 1976 and 1990, where postmenopausal women with clinically detected node-negative breast cancers &lt;3cm were randomized to receive tamoxifen versus not, was used for validation. Immunohistochemistry markers (n=727) and Agilent microarrays for MammaPrint risk scoring (n=652) were performed from formalin-fixed paraffin-embedded primary tumor blocks. Recursive partitioning was performed using the rpart package in R to select variables and construct a regression tree that best predicts 20-year breast cancer specific survival. Input variables include: age, period of diagnosis, grade, hormone receptor status, HER2 and Ki69 status, 70-gene risk categories (high, low but not ultra, or ultralow), treatment arm and tumor size; and cross-validation was used to select the final regression tree model.

Results: In this trial conducted in the era before mammographic screening, 58% and 42% were MammaPrint low and high risk, respectively, while 15% were above the ultralow threshold. In the tamoxifen treated arm, women with tumors above the ultralow threshold had no deaths at 15 years and their 20-year disease-specific survival rates of 97%; whereas if untreated, their survival rates were 94%. Recursive partitioning identified the ultralow threshold classification as the first primary split in the model. Once the indolent tumors were partitioned out, among women with tumors below the ultralow threshold, the next most prognostic feature was size, where patients with tumors &gt;20mm have worse breast cancer specific survival. The last split in the model divides the patients with tumors ≤20mm into 70-gene high risk vs low but not ultralow risk groups.

Conclusions and Relevance: A threshold of the 70-gene MammaPrint assay can identify patients with indolent disease whose long-term risk of death from breast cancer after surgery alone is exceedingly low. This threshold emerged as the most prognostic variable, followed by tumor size, and mammaprint high vs. low but not ultralow in our recursive partitioning analysis. This suggests that finding indolent tumors early at a small size may not have much impact on patient outcome. Determining the presence of an ultralow risk breast cancer may prevent overtreatment. Conversely, once the indolent tumors are taken out of consideration, both biology and size impact outcome, and finding these tumors at a small size is likely still important and supports screening in this postmenopausal node negative population.

Citation Format: Esserman LJ, Yau C, Thompson CK, van't Veer LJ, Borowsky AD, Hoadley KA, Tobin NP, Nordenskjöld B, Fornander T, Stål O, Benz CC, Lindström LS. Identification of breast cancers with an indolent disease course: 70 gene indolent threshold validation in a Swedish randomized trial of tamoxifen vs. not, with 20 year outcomes [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD7-02.

Abstract P2-05-03: Intra-tumor heterogeneity of the estrogen receptor predicts less benefit from tamoxifen therapy and poor long-term breast cancer patient survival – Retrospective analyses of the STO-3 randomized trial

Background

We and others have shown that the clinically used breast cancer markers alter their expression throughout tumor progression, influencing patient survival (Lindström et al, JCO 2012). What are the likely explanations to our findings? Here, we aimed to determine whether breast cancer intra-tumor heterogeneity of the estrogen receptor (ER) is a marker of tumor aggressiveness and benefit of tamoxifen therapy in a large randomized trial.

Material and methods

The Stockholm Tamoxifen (STO-3) trial enrolled postmenopausal lymph node negative breast cancer patients with a tumor size of less than 30 mm, between 1976 and 1990, to be randomized to receive adjuvant tamoxifen versus not. From the original randomized trial cohort approximately half of the patients (778 patients) had primary tumor formalin-fixed paraffin-embedded blocks available and were included in our study. No significant differences in age and period of diagnosis, type of surgery received, receptor status, tumor grade and size were observed between the treatment arms.

All tumor slides were immunostained in a central laboratory using the SP1 antibody. ER slides were scored by two independent breast cancer pathologists assessing the fraction of cancer cells for each ER intensity level (0, +1, +2 or +3) compared to established standards. The resulting distribution of ER stained tumor cells defines intra-tumor heterogeneity of ER (Rao's quadratic entropy (QE),Potts et al, Lab Invest 2012). Intra-tumor heterogeneity was categorized using the third tertile as cut-off for high heterogeneity (726 patients).

Analyses of long-term breast cancer specific survival (25 years) by intra-tumor heterogeneity of ER were performed using univariate Kaplan-Meier and multivariate Cox proportional hazard modeling adjusting for treatment arm, age and period of diagnoses, ER, progesterone receptor (PR), HER2, Ki-67, tumor grade, and tumor size. Further, a test of correlation was performed to investigate whether intra-tumor heterogeneity of ER was correlated to the percentage of ER positive cells, the H-Score or the Luminal A and B subtype (PAM50).

Results

In the univariate Kaplan-Meier analyses, a statistically significant difference in long-term survival by intra-tumor heterogeneity of ER was seen for all patients (log rank, P=0.018), tamoxifen treated arm (log rank, P=0.0033), but not untreated arm (log rank, P=0.19). However in the multivariate analysis, patients with high intra-tumor heterogeneity of ER in the treated arm as well as in the untreated arm had an almost two-fold increased long-term risk of fatal breast cancer disease as compared to patients with low or intermediate heterogeneity (Treated arm: HR, 2.06; 95% CI, 1.04-4.07 and Untreated arm: HR, 1.71; 95% CI, 1.01-2.87).

No significant correlation of intra-tumor heterogeneity to the tested variables was seen.

Conclusions

Patients with high intra-tumor heterogeneity of ER had less benefit from tamoxifen therapy and an increased long-term risk of fatal breast cancer disease. Our findings should be clinically relevant since therapy benefit was evaluated in a randomized trial with long-term follow-up.

Citation Format: Lindström LS, Yau C, Czene K, Thompson CK, van't Veer LJ, Nordenskjöld B, Stål O, Fornander T, Benz CC, Borowsky AD, Esserman LJ. Intra-tumor heterogeneity of the estrogen receptor predicts less benefit from tamoxifen therapy and poor long-term breast cancer patient survival – Retrospective analyses of the STO-3 randomized trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-05-03.

Histological grade provides significant prognostic information in addition to breast cancer subtypes defined according to St Gallen 2013

BACKGROUND

The St Gallen surrogate definition of the intrinsic subtypes of breast cancer consist of five subgroups based on estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor type 2 (HER2), and Ki-67. PgR and Ki-67 are used for discriminating between the 'Luminal A-like' and 'Luminal B-like (HER2-negative)' subtypes. Histological grade (G) has prognostic value in breast cancer; however, its relationship to the St Gallen subtypes is not clear. Based on a previous pilot study, we hypothesized that G could be a primary discriminator for ER-positive/HER2-negative breast cancers that were G1 or G3, whereas Ki-67 and PgR could provide additional prognostic information specifically for patients with G2 tumors. To test this hypothesis, a larger patient cohort was examined.

PATIENTS AND METHODS

Six hundred seventy-one patients (≥35 years of age, pT1-2, pN0-1) with ER-positive/HER2-negative breast cancer and complete data for PgR, Ki-67, G, lymph node status, tumor size, age, and distant disease-free survival (DDFS; median follow-up 9.2 years) were included.

RESULTS

'Luminal A-like' tumors were mostly G1 or G2 (90%) whereas 'Luminal B-like' tumors were mostly G2 or G3 (87%) and corresponded with good and poor DDFS, respectively. In 'Luminal B-like' tumors that were G1 (n = 23), no metastasis occurred, whereas 14 of 40 'Luminal A-like' tumors that were G3 metastasized. In the G2 subgroup, low PgR and high Ki-67 were associated with an increased risk of distant metastases, hazard ratio (HR) and 95% confidence interval (CI) 1.8 (0.95-3.4) and 1.5 (0.80-2.8), respectively.

CONCLUSIONS

Patients with ER-positive/HER2-negative/G1 breast cancer have a good prognosis, similar to that of 'Luminal A-like', while those with ER-positive/HER2-negative/G3 breast cancer have a worse prognosis, similar to that of 'Luminal B-like', when assessed independently of PgR and Ki-67. Therapy decisions based on Ki-67 and PgR might thus be restricted to the subgroup G2.

Progesterone receptor positivity is a predictor of long-term benefit from adjuvant tamoxifen treatment of estrogen receptor positive breast cancer

Purpose

The independent predictive information from progesterone receptor (PgR) positivity for breast cancer treated with tamoxifen has been questioned after an overview by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). However, the studies in the overview were to a large content performed before modern PgR immunohistochemistry (IHC) was developed. We therefore investigated the predictive value of PgR determined with IHC in estrogen receptor (ER)-positive tumors from patients participating in the Stockholm trial of adjuvant tamoxifen therapy.

Methods

The Stockholm Breast Cancer Study Group conducted a randomized trial during 1976 through 1990 comparing adjuvant tamoxifen versus control. The patients were stratified according to tumor size and lymph node status in high-risk and low-risk groups. In this study, we evaluated 618 patients with ER-positive “low-risk” breast cancer (size ≤ 30 mm, lymph node-negative) for whom PgR was determined by IHC at one pathology laboratory. The median time of follow-up was 21 years.

Results

Patients with ER-positive tumors that were also PgR-positive by IHC did benefit from tamoxifen, while we could not show any long-term benefit for those with tumors positive for ER only (recurrence rate ratio 0.43, 95 % CI 0.29–0.62 and 0.87, 95 % CI 0.52–1.46, respectively). We further investigated the influence of different levels of PgR positivity on recurrence risk. The results show that at all receptor levels with ≥10 % stained PgR-positive cells, the patients did benefit from tamoxifen. There was no clear linear trend in benefit with increasing proportion of stained cells.

Conclusions

PgR positivity determined by IHC is a marker indicating long-term benefit from adjuvant tamoxifen in patients with ER-positive tumors.

Electronic supplementary material

The online version of this article (doi:10.1007/s10549-016-4007-5) contains supplementary material, which is available to authorized users.

High expression of stromal PDGFRβ is associated with reduced benefit of tamoxifen in breast cancer

Cancer‐associated fibroblasts (CAFs) regulate tumour growth, metastasis and response to treatment. Recent studies indicate the existence of functionally distinct CAF subsets. Suggested mechanisms whereby CAFs can impact on treatment response include paracrine signalling affecting cancer cell drug sensitivity and effects on tumour drug uptake. PDGFRβ is an important regulator of fibroblasts. Experimental studies have linked PDGFRβ‐positive fibroblasts to metastasis and also to reduced tumour drug uptake. This study has investigated the potential role of PDGFRβ‐positive fibroblasts in response to adjuvant tamoxifen treatment of breast cancer. Analyses of two breast cancer collections from randomised studies analysing adjuvant tamoxifen treatment in early breast cancer demonstrated significant benefit of tamoxifen in the group with low stromal PDGFRβ, which was not observed in the group with high stromal PDGFRβ. In general terms these findings provide novel evidence, derived from analyses of randomised clinical studies, of response‐predictive capacity of a marker‐defined subset of CAFs and, more specifically, identify stromal PDGFRβ as a marker related to tamoxifen benefit in early breast cancer.

Two Years of Adjuvant Tamoxifen Provides a Survival Benefit Compared With No Systemic Treatment in Premenopausal Patients With Primary Breast Cancer: Long-Term Follow-Up (> 25 years) of the Phase III SBII:2pre Trial

PURPOSE

The aim of this study was to evaluate the long-term effect of 2 years of adjuvant tamoxifen compared with no systemic treatment (control) in premenopausal patients with breast cancer over different time periods through long-term (> 25 years) follow-up.

PATIENTS AND METHODS

Premenopausal patients with primary breast cancer (N = 564) were randomly assigned to 2 years of tamoxifen (n = 276) or no systemic treatment (n = 288). Data regarding date and cause of death were obtained from the Swedish Cause of Death Register. End points were cumulative mortality (CM) and cumulative breast cancer-related mortality (CBCM). The median follow-up for the 250 patients still alive in April 2014 was 26.3 years (range, 22.7 to 29.7 years).

RESULTS

In patients with estrogen receptor-positive tumors (n = 362), tamoxifen was associated with a marginal reduction in CM (hazard ratio [HR], 0.77; 95% CI, 0.58 to 1.03; P = .075) and a significant reduction in CBCM (HR, 0.73; 95% CI, 0.53 to 0.99; P = .046). The effect seemed to vary over time (CM years 0 to 5: HR, 1.05; 95% CI, 0.64 to 1.73; years > 5 to 15: HR, 0.58; 95% CI, 0.37 to 0.91; and after 15 years: HR, 0.82; 95% CI, 0.48 to 1.42; CBCM years 0 to 5: HR, 1.09; 95% CI, 0.65 to 1.82; years > 5 to 15: HR, 0.53; 95% CI, 0.33 to 0.86; and after 15 years: HR, 0.72; 95% CI, 0.36 to 1.44).

CONCLUSION

Two years of adjuvant tamoxifen resulted in a long-term survival benefit in premenopausal patients with estrogen receptor-positive primary breast cancer.

ERRα Is a Marker of Tamoxifen Response and Survival in Triple-Negative Breast Cancer

PURPOSE

Estrogen-related receptor alpha (ERRα) signaling has recently been implicated in breast cancer. We investigated the clinical value of ERRα in randomized cohorts of tamoxifen-treated and adjuvant-untreated patients.

EXPERIMENTAL DESIGN

Cox proportional hazards regression was used to evaluate the significance of associations between ERRα gene expression levels and patient DMFS in a previously published microarray dataset representing 2,000 breast tumor cases derived from multiple medical centers worldwide. The 912 tumors used for immunostaining were from a tamoxifen-randomized primary breast cancer trial conducted in Stockholm, Sweden, during 1976-1990. Mouse model was used to study the effect of tamoxifen treatment on lung colonization of MDA-MB-231 control cells and MDA-MB-231 cells with stable knockdown of ERRα. The phenotypic effects associated with ERRα modulation were studied using immunoblotting analyses and wound-healing assay.

RESULTS

We found that in ER-negative and triple-negative breast cancer (TNBC) adjuvant-untreated patients, ERRα expression indicated worse prognosis and correlated with poor outcome predictors. However, in tamoxifen-treated patients, an improved outcome was observed with high ERRα gene and protein expression. Reduced ERRα expression was oncogenic in the presence of tamoxifen, measured by in vitro proliferation and migration assays and in vivo metastasis studies.

CONCLUSIONS

Taken together, these data show that ERRα expression predicts response to tamoxifen treatment, and ERRα could be a biomarker of tamoxifen sensitivity and a prognostic factor in TNBC.