Survival Outcomes, Digital TILs, and On-treatment PET/CT During Neoadjuvant Therapy for HER2-positive Breast Cancer: Results from the Randomized PREDIX HER2 Trial

PURPOSE

PREDIX HER2 is a randomized Phase II trial that compared neoadjuvant docetaxel, trastuzumab, and pertuzumab (THP) with trastuzumab emtansine (T-DM1) for HER2-positive breast cancer. Rates of pathologic complete response (pCR) did not differ between the two groups. Here, we present the survival outcomes from PREDIX HER2 and investigate metabolic response and tumor-infiltrating lymphocytes (TIL) as prognostic factors.

PATIENTS AND METHODS

In total, 202 patients with HER2-positive breast cancer were enrolled and 197 patients received six cycles of either THP or T-DM1. Secondary endpoints included event-free survival (EFS), recurrence-free survival (RFS), and overall survival (OS). Assessment with PET/CT was performed at baseline, after two and six treatment cycles. TILs were assessed manually at baseline biopsies, while image-based evaluation of TILs [digital TILs (DTIL)] was performed in digitized full-face sections.

RESULTS

After a median follow-up of 5.21 years, there was no difference between the two treatment groups in terms of EFS [HR = 1.26; 95% confidence interval (CI), 0.54-2.91], RFS (HR = 0.69; 95% CI, 0.24-1.93), or OS (HR = 0.52; 95% CI, 0.09-2.82). Higher SUVmax at cycle 2 (C2) predicted lower pCR (ORadj = 0.65; 95% CI, 0.48-0.87; P = 0.005) and worse EFS (HRadj = 1.27; 95% CI, 1.12-1.41; P < 0.001). Baseline TILs and DTILs provided additional prognostic information to clinical parameters and C2 SUVmax.

CONCLUSIONS

Long-term outcomes following neoadjuvant T-DM1 were similar to neoadjuvant THP. SUVmax after two cycles of neoadjuvant therapy for HER2-positive breast cancer may be an independent predictor of both short- and long-term outcomes. Combined assessment with TILs may facilitate early selection of poor responders for alternative treatment strategies.

Combined assessment of metabolic response and tumor infiltrating lymphocytes as a predictor of outcomes following neoadjuvant therapy for HER2-positive breast cancer: Results from the randomized PREDIX HER2 trial

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Background: Abundance of tumor infiltrating lymphocytes (TIL) is prognostic in early HER2-positive breast cancer (BC). Response to neoadjuvant therapy (NAT) according to positron emission tomography combined with computed tomography (PET-CT) has been shown to predict pathologic complete response (pCR). There is paucity of data regarding long-term prognostication using PET-CT and the potential value of the combined assessment of both these biomarkers. Methods: PREDIX HER2 (NCT02568839) is a prospective randomized phase 2 trial that compared standard NAT (docetaxel, trastuzumab, pertuzumab) with trastuzumab emtansine, in patients with HER2-positive BC. Overall, 202 patients were included (197 evaluable) and the primary efficacy analysis showed no difference in pCR or event-free survival (EFS) between the two groups (Hatschek, JAMA Oncology 2021). Assessment with fluorine 18–labeled fluorodeoxyglucose PET-CT was performed at baseline and after 2 and 6 treatment cycles, and SUVmax was evaluated as a continuous variable. TILs were assessed at baseline biopsies according to guidelines from the International TIL Working Group (J.H.). The aim of this secondary analysis was to investigate the combined assessment of TIL and PET-CT as an early predictor of response to NAT. Results: Overall, 112 patients underwent baseline PET-CT and 109 after C2, whereas 173 had baseline TIL. In multivariable analysis, baseline SUVmax did not predict pCR (ORadj= 1.04, 95% CI 0.97-1.12, p = 0.259) or EFS (HRadj= 1.07, 95% CI 0.98-1.17, p = 0.117). In contrast, higher SUVmax at C2 predicted lower pCR (ORadj= 0.65, 95% CI 0.48-0.87, p = 0.005) and worse EFS (HRadj= 1.18, 95% CI 1.04-1.34, p = 0.01). Baseline TIL > 10% (median cut-off) provided additional prognostic information to clinical parameters (stage and hormone receptor expression) and C2 SUVmax (LR-Δχ2 = 7.19, p = 0.007; ORadj= 3.52, 95% CI 1.37 – 9.06, p = 0.009). 75% of patients with high TIL and C2 SUVmax < 2.49 achieved pCR, compared with 13.8% of those with low TIL and high C2 SUVmax and 39.1%-41.3% for the intermediate groups (p = 0.001). Conclusions: SUVmax after two cycles of NAT for HER2-positive BC is an independent predictor of both short- and long-term outcomes. A combined assessment with TIL may facilitate early selection of good responders for de-escalation and poor responders for alternative treatment strategies. Clinical trial information: NCT02568839.

Neoadjuvant Trastuzumab, Pertuzumab, and Docetaxel vs Trastuzumab Emtansine in Patients With ERBB2-Positive Breast Cancer: A Phase 2 Randomized Clinical Trial

Importance

Trastuzumab emtansine (T-DM1) is presently approved for treatment of advanced breast cancer and after incomplete response to neoadjuvant therapy, but the potential of T-DM1 as monotherapy is so far unknown.

Objective

To assess pathologic complete response (pCR) to standard neoadjuvant therapy of combination docetaxel, trastuzumab, and pertuzumab (DTP) vs T-DM1 monotherapy in patients with ERBB2 (formerly HER2)-positive breast cancer.

Design, Setting, and Participants

This randomized phase 2 trial, conducted at 9 sites in Sweden, enrolled 202 patients between December 1, 2014, and October 31, 2018. Participants were 18 years or older, with ERBB2-positive tumors larger than 20 mm and/or verified lymph node metastases. Analysis was performed on an intention-to-treat basis.

Interventions

Patients were randomized to receive 6 cycles of DTP (standard group) or T-DM1 (investigational group). Crossover was recommended at lack of response or occurrence of intolerable toxic effects. Assessment with fluorine 18-labeled fluorodeoxyglucose (18F-FDG) positron emission tomography combined with computed tomography (PET-CT) was performed at baseline and after 2 and 6 treatment cycles.

Main Outcome and Measures

Pathologic complete response, defined as ypT0 or Tis ypN0. Secondary end points were clinical and radiologic objective response; event-free survival, invasive disease-free survival, distant disease-free survival, and overall survival; safety; health-related quality of life (HRQoL); functional and biological tumor characteristics; and frequency of breast-conserving surgery.

Results

Overall, 202 patients were randomized; 197 (99 women in the standard group [median age, 51 years (range, 26-73 years)] and 98 women in the investigational group [median age, 53 years (range, 28-74 years)]) were evaluable for the primary end point. Pathologic complete response was achieved in 45 patients in the standard group (45.5%; 95% CI 35.4%-55.8%) and 43 patients in the investigational group (43.9%; 95% CI 33.9%-54.3%). The difference was not statistically significant (P = .82). In a subgroup analysis, the pCR rate was higher in hormone receptor-negative tumors than in hormone receptor-positive tumors in both treatment groups (45 of 72 [62.5%] vs 45 of 125 [36.0%]). Three patients in the T-DM1 group experienced progression during therapy. In an exploratory analysis, tumor-infiltrating lymphocytes at 10% or more (median) estimated pCR significantly (odds ratio, 2.76; 95% CI, 1.42-5.36; P = .003). Response evaluation with 18F-FDG PET-CT revealed a relative decrease of maximum standardized uptake value by more than 31.3% (median) was associated with pCR (odds ratio, 6.67, 95% CI, 2.38-20.00; P < .001).

Conclusions and Relevance

In this study, treatment with standard neoadjuvant combination DTP was equal to T-DM1.

Trial Registrations

ClinicalTrials.gov Identifier: NCT02568839; EudraCT number: 2014-000808-10.

Prognostic role of serum thymidine kinase 1 kinetics during neoadjuvant chemotherapy for early breast cancer

Background

Emerging data support the use of thymidine kinase 1 (TK1) activity as a prognostic marker and for monitoring of response in breast cancer (BC). The long-term prognostic value of TK1 kinetics during neoadjuvant chemotherapy is unclear, which this study aimed to elucidate.

Methods

Material from patients enrolled to the single-arm prospective PROMIX trial of neoadjuvant epirubicin, docetaxel and bevacizumab for early BC was used. Ki67 in baseline biopsies was assessed both centrally and by automated digital imaging analysis. TK1 activity was measured from blood samples obtained at baseline and following two cycles of chemotherapy. The associations of TK1 and its kinetics as well as Ki67 with event-free survival and overall survival (OS) were evaluated using multivariable Cox regression models.

Results

Central Ki67 counting had excellent correlation with the results of digital image analysis (r = 0.814), but not with the diagnostic samples (r = 0.234), while it was independently prognostic for worse OS [adjusted hazard ratio (HR_adj) = 2.72, 95% confidence interval (CI) 1.19-6.21, P = 0.02]. Greater increase in TK1 activity after two cycles of chemotherapy resulted in improved event-free survival (HR_adj = 0.50, 95% CI 0.26-0.97, P = 0.04) and OS (HR_adj = 0.46, 95% CI 0.95, P = 0.04). There was significant interaction between the prognostic value of TK1 kinetics and Ki67 (p_interaction 0.04).

Conclusion

Serial measurement of serum TK1 activity during neoadjuvant chemotherapy provides long-term prognostic information in BC patients. The ease of obtaining serial samples for TK1 assessment motivates further evaluation in larger studies.

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This is a correlative analysis of a prospective phase II study on neoadjuvant chemotherapy for breast cancer.

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Serial measurement of serum TK1 activity during treatment provides independent long-term prognostic information.

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We demonstrate the validity and clinical utility of both central and automated image analysis-based Ki67 assessment.

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Finally, we explore the biologic correlations between TK1 and Ki67.

Assessment of early response biomarkers in relation to long-term survival in patients with HER2-negative breast cancer receiving neoadjuvant chemotherapy plus bevacizumab: Results from the Phase II PROMIX trial

Pathologic complete response (pCR) is a predictor for favorable outcome after neoadjuvant treatment in early breast cancer. Modulation of gene expression may also provide early readouts of biological activity and prognosis, offering the possibility for timely response-guided treatment adjustment. The role of early transcriptional changes in predicting response to neoadjuvant chemotherapy plus bevacizumab was investigated. One-hundred-and-fifty patients with large, operable and locally advanced HER2-negative breast cancer received epirubicin and docetaxel, with the addition of bevacizumab. Patients underwent tumor biopsies at baseline, after Cycle 2 and at the time of surgery. The primary end point, pCR, and its relation with the secondary endpoints event-free survival (EFS), overall survival (OS) and gene expression profiles, are reported. The pCR rate was 13% (95% CI 8.6-20.2), with significantly more pCRs among triple-negative [28% (95% CI 14.8-45.4)] than among hormone receptor positive (HR+) tumors [9% (95% CI 4.6-16.3); (OR = 3.9 [CI = 1.5-10.3])]. pCR rates were not associated with EFS or OS. PAM50 subtypes significantly changed after Cycle 2 (p = 0.03) and an index of absolute changes in PAM50 correlations between these time-points was associated with EFS [HR = 0.62 (CI = 0.3-1.1)]. In univariable analyses, signatures for angiogenesis, proliferation, estrogen receptor signaling, invasion and metastasis, and immune response, measured after Cycle 2, were associated with pCR in HR+ tumors. Evaluation of changes in molecular subtypes and other signatures early in the course of neoadjuvant treatment may be predictive of pCR and EFS. These factors may help guide further treatment and should be considered when designing neoadjuvant trials.

Abstract P1-10-05: Omitting radiotherapy in women ≥ 65 years with early breast cancer and favorable histopathology after breast-conserving surgery, sentinel node biopsy and adjuvant endocrine therapy is safe

Background: The benefit of radiotherapy in older women with endocrine responsive early breast cancer treated with breast-conserving surgery and endocrine therapy is unclear. The aim of this study was to verify if omission of radiotherapy in a predefined cohort of patients with good prognosis early breast cancer after breast conservation is safe.

Methods: Eligibility criteria were: consecutive patients with age ≥ 65 years, breast-conserving surgery (sector resection + sentinel node biopsy), clear margins, unifocal T 1 N0, Elston grade 1 and 2, estrogen receptor-positive. After informed consent adjuvant endocrine therapy, either tamoxifen or an aromatase inhibitor, was prescribed for 5 years. Primary endpoint was ipsilateral breast tumor recurrence (IBTR). Secondary endpoints were contralateral breast cancer, recurrence-free survival (RFS) and overall survival (OS).

Results: Between 2006 and 2012, we included 603 women from 14 Swedish centers. Two patients did not fulfill the inclusion criteria and were excluded from the analysis. Median age was 71 years (range 65 to 90). At a median follow-up of 59 months (range 2 to 110) 13 IBTR (cumulative incidence at five years, 1.3% (95% CI, 0.6% to 2.7%), 4 regional recurrences (one combined with IBTR), 2 distant recurrences both without IBTR or regional recurrence and 11 contralateral breast cancers was observed. Twenty-nine patients were diagnosed with tumors of other origin. Seven of them were endometrial cancers. There were 39 deaths. Only one of the deaths (2.6%) was due to breast cancer and 11 (28.2%) were due to other cancers (2 endometrial cancers). Five-year overall survival was 93.9% (95% CI, 91.4% to 95.7%).

Conclusion: This study demonstrates, with a median follow-up of 59 months, that breast-conserving surgery and endocrine therapy without radiotherapy is a safe treatment option in women with early breast cancer and favorable histopathology aged ≥ 65 years. The risk of IBTR is comparable to the risk of contralateral breast cancer. The low rate of breast cancer deaths indicates that breast cancer mortality is of secondary importance in this subset of women.

Citation Format: Villman KKA, Wickberg Å, Killander F, Lindman H, Bjöhle J, Edlund P, Tennvall-Nittby L, Bachmeier K, Carlberg M, Blomqvist C, Ahlgren J, Liljegren G. Omitting radiotherapy in women ≥ 65 years with early breast cancer and favorable histopathology after breast-conserving surgery, sentinel node biopsy and adjuvant endocrine therapy is safe [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 P1-10-05.

Abstract P3-11-14: Is pathologic complete response (pCR) a valid marker of outcome even in large breast cancer? Clinical results from a neoadjuvant trial using a combination of epirubicin, docetaxel and bevacizumab (PROMIX)

Background: Several randomized trials have proven that preoperative chemotherapy is equivalent to adjuvant treatment, and allows for clinical and radiological assessment of efficacy in vivo. Recent results show that response-guided neoadjuvant therapy is a favorable policy for hormone receptor positive tumors, while pCR predicts prognosis for triple-negative (TNBC) and HER2 positive breast cancer (von Minckwitz 2013; Cortazar 2014). Since 2012 the FDA accepts pCR (ypT0 ypN0) as endpoint for accelerated drug approval.

Methods: In total, 150 women 18 years or older with verified HER2 negative breast cancer suitable for primary medical treatment were included in the trial between September 2008 and December 2011. The patients received two courses of epirubicin and docetaxel (Taxotere®), both 75mg/m2 for the 1st two courses, followed by the same treatment with addition of bevacizumab (Avastin®) 15 mg/kg for 4 additional courses. Clinical and radiological evaluations with mammography and ultrasound were performed before start and after courses 2, 4 and 6. Core biopsies were taken before start, after 2 courses, and at time of surgery. Blood samples were drawn before and 24 hours after the first 4 courses.

Results: Median age was 49 years, range: 27 to 70 years; 73% were reported as ductal, 15% as lobular, and 12% as rare histological types. Mean tumor size was 59 mm, median 55 mm, range: 20-180 mm; 3 tumors (2.0%) were reported as inflammatory, and 13 (8.7%) presented with skin involvement (T4b). Enlarged axillary nodes were found in 102 patients (68%) before start of treatment, 77 of these (64%) verified as metastatic. SNB in cases of normal axillary status was performed in 16 cases, in 9 cases (8%) with positive finding. Supra- or infraclavicular node involvement was verified in 20 cases (13%). 25% of all tumors were ER- and/or PR-negative, tumor grade based on a diagnostic biopsy was evaluable in only 83 cases. Of these, 4 (5%) were grade I, 46 (55%) grade II, and 33 (40%) grade III. Mean proliferation count (Ki67) was 37%, median 30%, range 1-90%. Breakdown into intrinsic subtypes based on immunohistochemistry defined 68 (46%) as luminal A-like, 36 (24%) as luminal B-like, and 44 (30%) as TNBC. pCR was achieved in 20 cases, 3 (2%) luminal A-like, 5 (3.4%) luminal B-like and 12 (8.2%) TNBC. After 2.2 years of follow-up, 35 patients (23.3%) have experienced recurrence and 18 of these (12%) have deceased due to breast cancer, among these 6 despite pCR, 2 classified as luminal B-like, and 4 as TNBC. The molecular subtype of the tumor predicted outcome, but pCR was not in our material, even after adjustment for tumor size at diagnosis, a predictor of favorable outcome. The number of events in relation to molecular subtypes is however limited. Updated outcome data will be presented.

Conclusions: The present trial does not confirm previously reported observations that pCR is a marker of favorable prognosis. One possible explanation is that unfavorable biological characteristics, particularly heterogeneity, may increase with tumor burden. Genomic and proteomic analyses are currently ongoing.

Citation Format: Thomas Hatschek, Judith Bjöhle, Elisabet Lidbrink, Tobias Lekberg, Niklas Loman, Anna von Wachenfeldt Väppling, Martin Söderberg, Zakaria Einbeigi, Lena Carlsson, Henrik Lindman, Irma Fredriksson, Jan Frisell, Lars Löfgren, Lisa Rydén, Mats Hellström, Mårten Fernö, Jonas Bergh. Is pathologic complete response (pCR) a valid marker of outcome even in large breast cancer? Clinical results from a neoadjuvant trial using a combination of epirubicin, docetaxel and bevacizumab (PROMIX) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-11-14.

Abstract P2-05-02: Preliminary translational results from PROMIX, a phase II trial of preoperative chemotherapy with the addition of bevacizumab in large operable and locally advanced HER2-negative breast cancer

Background: Preoperative chemotherapy in breast cancer (bc) provides unique possibilities to evaluate effects of therapy by studying response and changes in the tumor during the course of treatment. A pathologic complete response (pCR) correlates positively with long term prognosis in high-proliferating bc. In triple negative bc (TNBC) the prognosis was still relatively serious in cases with pCR in one large meta-analysis (Cortazar Lancet 2014).

Methods: 150 cases were included in this multicenter study, and treated with six cycles of epirubicin and docetaxel, adding bevacizumab from cycle 3, before surgery. Core needle biopsies were collected at free hand or with ultrasound (US) guidance and snap frozen at base-line and after cycle 2, tissue was also collected at surgery. Subtyping was performed using immunohistochemistry (IHC) of ER, Ki67 and HER2 according to modified St Gallen criteria; and using bead array gene expression profiling (GEX) according to PAM50.

Results: Biopsies were successfully retrieved from 145/150 pts at baseline, 138 after cycle 2 and 139 at surgery. The mRNA yield was adequate for GEX from 123/145 (85%) at baseline, 82/138 (59%) at cycle 2 and 71/139 (51%) at surgery, the decrease being a result of tumor shrinkage during treatment.

Initial PAM50 subtypes were as follows: luminal A (LA) 20%, luminal B (LB) 45%, HER2 5 %, basal like (BL) 22% and normal like (NL) 8%. PAM50 at baseline differed compared to IHC subtypes. Among IHC defined LA-like cases 15/33 (45%) were classified as LB by PAM50. Similarly, among IHC LB-like 22/57 (39%) were classified as non-LB (6 basal, 8 LA, 3 HER2 and 5 NL), while among IHC TNBC 7/28 (25%) were classified as non-BL subtypes (1 LA, 3 HER2 and 3 NL).

Of the pts with a baseline GEX analysis, 17 (14%) achieved a pCR. The observed pCR rates among PAM50 subtypes were: LA 8%, LB 5%, HER2 17%, BL 53% and NL 20%. For non-pCR cases, 39/52 (75%) of the tumors changed PAM50 subtype between baseline and surgery. The majority changed to the NL subtype. 33% of the LB tumors changed to the LA subtype.

Currently, after 2.2 years of follow-up, 16 pts are deceased due to bc. Among BL cases, 6/9 pts with a pCR at surgery remain alive; while 3/9 have died from bc. Exploratory analyses using functional gene modules (Desmedt Clin Cancer Res 2008) suggest that patients with BL tumors who have died have higher scores for PLAU/invasion and lower scores for STAT1/immune response compared with those who are still alive. Tumor size at baseline did not obviously correlate with outcome.

Conclusion: We show that biological material can be retrieved from a substantial fraction of cases treated within a multicenter study of preoperative chemotherapy. The success rate may be ameliorated by routine use of US guidance. The distribution of subtypes differs between modified IHC St Gallen criteria and PAM50, especially within the luminal subtypes. The pCR rate is highest among cases with a BL tumor at baseline. Shift of the gene signature between different subtypes during the course of treatment is frequent. In this set of relatively large tumors, the prognosis among BL bc appears to be adverse in spite of a pCR.

Citation Format: Niklas Loman, Ida Johansson, Judith Bjöhle, Jan Frisell, Tobias Lekberg, Lisa Rydén, Anna von Wachenfeldt, Jonas Bergh, Thomas Hatschek, Ingrid Hedenfalk. Preliminary translational results from PROMIX, a phase II trial of preoperative chemotherapy with the addition of bevacizumab in large operable and locally advanced HER2-negative breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-05-02.

Multi-level gene expression signatures, but not binary, outperform Ki67 for the long term prognostication of breast cancer patients

Proliferation-related gene signatures have been proposed to aid breast cancer management by providing reproducible prognostic and predictive information on a patient-by-patient basis. It is unclear however, whether a less demanding assessment of cell division rate (as determined in clinical setting by expression of Ki67) can function in place of gene profiling. We investigated agreement between literature-, distribution-based, as well as signature-derived values for Ki67, relative to the genomic grade index (GGI), 70-gene signature, p53 signature, recurrence score (RS), and the molecular subtype models of Sorlie, Hu, and Parker in representative sets of 253 and 159 breast cancers with a median follow-up of 13 and 14.5 years, respectively. The relevance for breast cancer specific survival was also addressed in uni- and bivariate Cox models. Taking both cohorts into account, our broad approach identified ROC optimized Ki67 cutoffs in the range of 8-28%. With optimum signature-reproducing cutoffs, similarity in classification of individual tumors was higher for binary signatures (72-85%), than multi-level signatures (67-73%). Consistent with strong agreement, no prognostic superiority was noted for either Ki67 or the binary GGI, 70-gene and p53 signatures in the Uppsala dataset by bivariate analyses. In contrast, Ki67-independent prognostic capacity could be demonstrated for RS and molecular subtypes according to Sorlie, Hu and Parker in both datasets. Our results show that the added prognostic value of binary proliferation-related gene signatures is limited for Ki67-assessed breast cancers. More complex, multi-level descriptions have a greater potential in short- and long-term prognostication for biologically relevant breast cancer subgroups.

No difference in dose distribution in organs at risk in postmastectomy radiotherapy with or without breast implant reconstruction

The aim of this study was to quantify the variation in doses to organs at risk (ipsilateral lung and heart) and the clinical target volume (CTV) in the presence of breast implants. In this retrospective cohort study, patients were identified through the National Breast Cancer Register. Consecutive breast cancer patients undergoing mastectomy between 2009 and 2011 and completing a full course of postmastectomy radiotherapy (PMRT) were eligible. All included patients (n = 818) were identified in the ARIA© oncology information system and further stratified for immediate breast reconstruction (IBR+, n = 162) and no immediate breast reconstruction (IBR-, n = 656). Dose statistics for ipsilateral lung, heart and CTV were retrieved from the system. Radiation plans for patients with chest wall (CW) only (n = 242) and CW plus lymph nodes (n = 576) irradiation were studied separately.

The outcome variables were dichotomized as follows: lung, V_20Gy ≤ 30% vs. V_20Gy > 30%; heart, D_mean ≤ 5 Gy vs. D_mean > 5 Gy; CTV, V_95% ≥ median vs. V_95% < median.

In the univariate and multivariate regression models no correlation between potential confounders (i.e. breast reconstruction, side of PMRT, CW index) and the outcome variables was found. Multivariate analysis of CW plus lymph nodes radiation plans, for example, showed no association of breast reconstruction with dosimetric outcomes in neither lung nor heart- lung V_20Gy (odds ratio [OR]: 0.6, 95%CI, 0.4 to 1.0, p = 0.07) or heart D_mean (OR: 1.2, 95%CI, 0.5 to 3.1, p = 0.72), respectively.

CTV was statistically significantly larger in the IBR+ group (i.e. included breast implant), but no correlation between the implant type and dosimetric characteristics of the organs at risk was revealed.

In the current study, the presence of breast implants during postmastectomy radiotherapy was not associated with increased doses to ipsilateral lung and heart, but CTV definition and its dosimetric characteristics urge further evaluation.

Serum thymidine kinase activity compared with CA 15-3 in locally advanced and metastatic breast cancer within a randomized trial

The primary objective was to estimate serum thymidine kinase 1 (TK1) activity, reflecting total body cell proliferation rate including cancer cell proliferation, in women with loco regional inoperable or metastatic breast cancer participating in a prospective and randomized study. Secondary objectives were to analyze TK1 in relation to progression-free survival (PFS), overall survival (OS), therapy response and other tumour characteristics, including CA 15-3, widely used as a standard serum marker for disease progression. TK1 and CA 15-3 were analysed in 198 serum samples collected prospectively from women included in the randomized TEX trial between December 2002 and June 2007. TK1 activity was determined by the ELISA based DiviTum™ assay, and CA 15-3 analyses was generated with the electrochemiluminescence immunoassay Cobas Elecsys CA 15-3 II. High pre-treatment TK1 activity predicted shorter PFS (10 vs. 15 months p = 0.02) and OS (21 vs. 38 months, p < 0.0001), respectively. After adjustment for age, metastatic site and study treatment TK1 showed a trend as predictor of PFS (p = 0.059) and was an independent prognostic factor for OS, (HR 1.81, 95 % confidence interval (CI) 1.26-2.61, p = 0.001). There was a trend of shortened OS for women with high CA 15-3 (p = 0.054) in univariate analysis, but not after adjustment for the above mentioned covariates. Both TK1 (p = 0.0011) and CA 15-3 (p = 0.0004) predicted response to treatment. There were statistically different distributions of TK1 and CA 15-3 in relation to the site of metastases. TK1 activity measured by DiviTum™ predicted therapy response, PFS and OS in loco regional inoperable or disseminated breast cancer. These results suggest that this factor is a useful serum marker. In the present material, a prognostic value of CA 15-3 could not be proven.

Intrinsic molecular signature of breast cancer in a population-based cohort of 412 patients

Background

Molecular markers and the rich biological information they contain have great potential for cancer diagnosis, prognostication and therapy prediction. So far, however, they have not superseded routine histopathology and staging criteria, partly because the few studies performed on molecular subtyping have had little validation and limited clinical characterization.

Methods

We obtained gene expression and clinical data for 412 breast cancers obtained from population-based cohorts of patients from Stockholm and Uppsala, Sweden. Using the intrinsic set of approximately 500 genes derived in the Norway/Stanford breast cancer data, we validated the existence of five molecular subtypes – basal-like, ERBB2, luminal A/B and normal-like – and characterized these subtypes extensively with the use of conventional clinical variables.

Results

We found an overall 77.5% concordance between the centroid prediction of the Swedish cohort by using the Norway/Stanford signature and the k-means clustering performed internally within the Swedish cohort. The highest rate of discordant assignments occurred between the luminal A and luminal B subtypes and between the luminal B and ERBB2 subtypes. The subtypes varied significantly in terms of grade (p < 0.001), p53 mutation (p < 0.001) and genomic instability (p = 0.01), but surprisingly there was little difference in lymph-node metastasis (p = 0.31). Furthermore, current users of hormone-replacement therapy were strikingly over-represented in the normal-like subgroup (p < 0.001). Separate analyses of the patients who received endocrine therapy and those who did not receive any adjuvant therapy supported the previous hypothesis that the basal-like subtype responded to adjuvant treatment, whereas the ERBB2 and luminal B subtypes were poor responders.

Conclusion

We found that the intrinsic molecular subtypes of breast cancer are broadly present in a diverse collection of patients from a population-based cohort in Sweden. The intrinsic gene set, originally selected to reveal stable tumor characteristics, was shown to have a strong correlation with progression-related properties such as grade, p53 mutation and genomic instability.

Gene expression in 16q is associated with survival and differs between Sørlie breast cancer subtypes

We have investigated the relationship between gene expression and chromosomal positions in 402 breast cancer patients. Using an overrepresentation approach based on Fisher's exact test, we identified disproportionate contributions of specific chromosomal positions to genes associated with survival. Our major finding is that the gene expression in the long arm of chromosome 16 stands out in its relationship to survival. This arm contributes 36 (18%) and 55 (11%) genes to lists negatively associated with recurrence-free survival (set to sizes 200 and 500). This is a highly disproportionate contribution from the 313 (2%) genes in this arm represented on the used Affymetrix U133A and B microarray platforms (Bonferroni corrected Fisher test: P < 2.2 x 10(-16)). We also demonstrate differential expression in 16q across tumor subtypes, which suggests that the ERBB2, basal, and luminal B tumors progress along a high grade-poor prognosis path, while luminal A and normal-like tumors progress along a low grade-good prognosis path, in accordance with a previously proposed model of tumor progression. We conclude that important biological information can be extracted from gene expression data in breast cancer by studying non-random connections between chromosomal positions and gene expression. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

Hormone-replacement therapy influences gene expression profiles and is associated with breast-cancer prognosis: a cohort study

BACKGROUND

Postmenopausal hormone-replacement therapy (HRT) increases breast-cancer risk. The influence of HRT on the biology of the primary tumor, however, is not well understood.

METHODS

We obtained breast-cancer gene expression profiles using Affymetrix human genome U133A arrays. We examined the relationship between HRT-regulated gene profiles, tumor characteristics, and recurrence-free survival in 72 postmenopausal women.

RESULTS

HRT use in patients with estrogen receptor (ER) protein positive tumors (n = 72) was associated with an altered regulation of 276 genes. Expression profiles based on these genes clustered ER-positive tumors into two molecular subclasses, one of which was associated with HRT use and had significantly better recurrence free survival despite lower ER levels. A comparison with external data suggested that gene regulation in tumors associated with HRT was negatively correlated with gene regulation induced by short-term estrogen exposure, but positively correlated with the effect of tamoxifen.

CONCLUSION

Our findings suggest that post-menopausal HRT use is associated with a distinct gene expression profile related to better recurrence-free survival and lower ER protein levels. Tentatively, HRT-associated gene expression in tumors resembles the effect of tamoxifen exposure on MCF-7 cells.

Gene expression profiling spares early breast cancer patients from adjuvant therapy: derived and validated in two population-based cohorts

Introduction

Adjuvant breast cancer therapy significantly improves survival, but overtreatment and undertreatment are major problems. Breast cancer expression profiling has so far mainly been used to identify women with a poor prognosis as candidates for adjuvant therapy but without demonstrated value for therapy prediction.

Methods

We obtained the gene expression profiles of 159 population-derived breast cancer patients, and used hierarchical clustering to identify the signature associated with prognosis and impact of adjuvant therapies, defined as distant metastasis or death within 5 years. Independent datasets of 76 treated population-derived Swedish patients, 135 untreated population-derived Swedish patients and 78 Dutch patients were used for validation. The inclusion and exclusion criteria for the studies of population-derived Swedish patients were defined.

Results

Among the 159 patients, a subset of 64 genes was found to give an optimal separation of patients with good and poor outcomes. Hierarchical clustering revealed three subgroups: patients who did well with therapy, patients who did well without therapy, and patients that failed to benefit from given therapy. The expression profile gave significantly better prognostication (odds ratio, 4.19; P = 0.007) (breast cancer end-points odds ratio, 10.64) compared with the Elston–Ellis histological grading (odds ratio of grade 2 vs 1 and grade 3 vs 1, 2.81 and 3.32 respectively; P = 0.24 and 0.16), tumor stage (odds ratio of stage 2 vs 1 and stage 3 vs 1, 1.11 and 1.28; P = 0.83 and 0.68) and age (odds ratio, 0.11; P = 0.55). The risk groups were consistent and validated in the independent Swedish and Dutch data sets used with 211 and 78 patients, respectively.

Conclusion

We have identified discriminatory gene expression signatures working both on untreated and systematically treated primary breast cancer patients with the potential to spare them from adjuvant therapy.

Gene expression profiling for prognosis using Cox regression

Given the promise of rich biological information in microarray data we will expect an increasing demand for a robust, practical and well-tested methodology to provide patient prognosis based on gene expression data. In standard settings, with few clinical predictors, such a methodology has been provided by the Cox proportional hazard model, but no corresponding methodology is available to deal with the full set of genes in microarray data. Furthermore, we want the procedure to be able to deal with the general survival data that include censored information. Conceptually such a procedure can be constructed quite easily, but its implementation will never be straightforward due to computational problems. We have developed an approach that relies on an extension of the Cox proportional likelihood that allows random effects parameters. In this approach, we use the full set of genes in the analysis and deal with survival data in the most general way. We describe the development of the model and the steps in the implementation, including a fast computational formula based on a subsampling of the risk set and the singular value decomposition. Finally, we illustrate the methodology using a data set obtained from a cohort of breast cancer patients.

Can axillary dissection be avoided by improved molecular biological diagnosis?

Axillary dissection is presently a routine staging procedure in the management of breast cancer. The use of adjuvant systemic treatment is largely based on the diagnosis of axillary metastases. Routine axillary dissection leads to acute and chronic side-effects in a large proportion of patients. The sentinel node technique is presently explored with the aim of decreasing the need for standard axillary dissection. A complementary way forward is to analyse the primary breast cancer for molecular markers with prognostic significance with reference to the risk for metastatic capacity and thereby obtain a 'biological staging' and identify those patients in need of systemic adjuvant therapy. A large number of molecular biological factors have been shown to have prognostic significance in breast cancer e.g. c-erbB-2, p53, uPA, PAI-I and VEGF. This article reviews the expression of these and other factors in the primary breast cancers in relation to the risk for axillary and systemic metastatic disease, with the long-term aim of excluding routine axillary dissection.

Radiation pneumonitis after breast cancer irradiation: analysis of the complication probability using the relative seriality model

BACKGROUND

Toxicity of the respiratory system is quite common after radiotherapy of thoracic tumors; breast cancer patients represent one of the groups for which there is also a long expected survival. The quantification of lung tissue response to irradiation is important in designing treatments associated with a minimum of complications and maximum tumor control.

METHODS

The study population consisted of 68 patients who received irradiation for breast cancer at Stage II. Radiation pneumonitis was retrospectively assessed on the basis of clinical symptoms and radiological findings. For each patient, a measure of the exposure (i.e., the lung dose-volume histogram [DVH]) and a measure of the outcome was available. Based on these data, a maximum likelihood fitting to the relative seriality model was performed. The uncertainties of the model parameters were calculated and their impact on the dose-response curve was studied. The optimum parameter set was then applied to 5 other patient groups treated for breast cancer, and the normal tissue complication probability (NTCP) was calculated. Each group was individuated by the radiotherapy treatment technique used; the dose distribution in the lung was described by a mean DVH and the incidence of radiation pneumonitis in each group was known. Lung radiosensitivity was assumed to be homogeneous through all of the calculations.

RESULTS

The relative seriality model could describe the dataset. The volume effect was found to be relevant in the description of radiation pneumonitis. Age was found to be associated with increased risk of radiation pneumonitis. Two distinct dose-response curves were obtained by splitting the group according to age. The impact of the parameter uncertainties on the dose-response curve was quite large. The parameter set determined could be used predictively on 3 of the 5 patient groups.

CONCLUSION

The complication data could be modeled with the relative seriality model. However, further independent datasets, classified according to the same endpoint, must be analyzed before introducing NTCP modeling in clinical practice.