21-Gene Assay to Inform Chemotherapy Benefit in Node-Positive Breast Cancer

Navigating precision: the crucial role of next-generation sequencing recurrence risk assessment in tailoring adjuvant therapy for hormone receptor-positive, human epidermal growth factor Receptor2-negative early breast cancer

Hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer is the most common subtype, representing over two-thirds of new diagnoses. Adjuvant therapy, which encompasses various medications and treatment durations, is the standard approach for managing early stage HR+ HER2- breast cancer. Optimizing treatment is essential to minimize unnecessary side effects while addressing the biological variability inherent in HR+/HER2- breast cancers. Incorporating biological biomarkers into treatment decisions, alongside traditional clinical factors, is vital. Gene expression assays can identify patients unlikely to benefit from adjuvant chemotherapy, thereby refining treatment strategies and improving risk assessment. This paper reviews evidence for several genomic tests, including Oncotype DX, MammaPrint, Breast Cancer Index, RucurIndex, and EndoPredict, which assist in tailoring adjuvant therapy. Additionally, we explore the role of liquid biopsies in personalizing treatment, emphasizing the importance of considering late relapse risks and potential benefits of extended systemic therapy for HR+/HER2- breast cancer patients.

Clinical applications of radiomics and deep learning in breast and lung cancer: A narrative literature review on current evidence and future perspectives

Radiomics, analysing quantitative features from medical imaging, has rapidly become an emerging field in translational oncology. Radiomics has been investigated in several neoplastic malignancies as it might allow for a non-invasive tumour characterization and for the identification of predictive and prognostic biomarkers. Over the last few years, evidence has been accumulating regarding potential clinical applications of machine learning in many crucial moments of cancer patients' history. However, the incorporation of radiomics in clinical decision-making process is still limited by low data reproducibility and study variability. Moreover, the need for prospective validations and standardizations is emerging. In this narrative review, we summarize current evidence regarding radiomic applications in high-incidence cancers (breast and lung) for screening, diagnosis, staging, treatment choice, response, and clinical outcome evaluation. We also discuss pro and cons of the radiomic approach, suggesting possible solutions to critical issues which might invalidate radiomics studies and propose future perspectives.

Prognostic value of the 21-Gene Breast Recurrence Score® assay for hormone receptor-positive/human epidermal growth factor 2-negative advanced breast cancer: subanalysis from Japan Breast Cancer Research Group-M07 (FUTURE trial)

PURPOSE

This study aimed to determine whether the 21-Gene Breast Recurrence Score® assay from primary breast tissue predicts the prognosis of patients with hormone receptor-positive and human epidermal growth factor 2-negative advanced breast cancers (ABCs) treated with fulvestrant monotherapy (Group A) and the addition of palbociclib combined with fulvestrant (Group B), which included those who had progression in Group A from the Japan Breast Cancer Research Group-M07 (FUTURE trial).

METHODS

Progression-free survival (PFS) and overall survival (OS) were compared using the log-rank test and Cox regression analysis based on original recurrence score (RS) categories (Low: 0-17, Intermediate: 18-30, High: 31-100) by treatment groups (A and B) and types of ABCs (recurrence and de novo stage IV).

RESULTS

In total, 102 patients [Low: n = 44 (43.1%), Intermediate: n = 38 (37.5%), High: n = 20 (19.6%)] in Group A, and 45 in Group B, who had progression in Group A were analyzed. The median follow-up time was 23.8 months for Group A and 8.9 months for Group B. Multivariate analysis in Group A showed that low-risk [hazard ratio (HR) 0.15, 95% confidence interval (CI) 0.04-0.53, P = 0.003] and intermediate-risk (HR 0.22, 95% CI 0.06-0.78) with de novo stage IV breast cancer were significantly associated with better prognosis compared to high-risk. However, no significant difference was observed among patients with recurrence. No prognostic significance was observed in Group B.

CONCLUSION

We found a distinct prognostic value of the 21-Gene Breast Recurrence Score® assay by the types of ABCs and a poor prognostic value of the high RS for patients with de novo stage IV BC treated with fulvestrant monotherapy. Further validations of these findings are required.

Irish national real-world analysis of the clinical and economic impact of 21-gene oncotype DX® testing in early-stage, 1-3 lymph node-positive, oestrogen receptor-positive, HER2-negative, breast cancer

PURPOSE

The treatment landscape of Oestrogen receptor-positive (ER-positive) breast cancer is evolving, with declining chemotherapy use as a result of Oncotype DX Breast Recurrence Score® testing. Results from the SWOG S1007 RxPONDER trial suggest that adjuvant chemotherapy may benefit some premenopausal women with ER-positive, HER2-negative disease with 1-3 positive lymph nodes (N1), and a Recurrence Score® (RS) of ≤ 25. Postmenopausal women with similar characteristics did not benefit from adjuvant chemotherapy. We examine the clinical and economic impact of Oncotype DX® testing on treatment decisions in patients with N1 disease in Ireland using real world data.

METHODS

From March 2011 to October 2022, a retrospective, cross-sectional observational study was performed of patients with ER-positive, HER2-negative N1 breast cancer, who had Oncotype DX testing across 5 of Ireland's largest cancer centres. Patients were classified into low risk (RS 0-13), intermediate risk (RS 14-25) and high risk (RS > 25). Data were collected via electronic patient records. Information regarding costing was provided primarily by pre-published sources.

RESULTS

A total of 828 N1 patients were included in this study. Post Oncotype DX testing, 480 patients (58%) were spared chemotherapy. Of the patients who had a change in chemotherapy recommendation based on Oncotype DX testing, 271 (56%), 205 (43%), 4 (1%) had a RS result of 0-13, 14-25 and > 25 respectively. Use of Oncotype DX testing was associated with a 58% reduction in chemotherapy administration overall. This resulted in estimated savings of over €6 million in treatment costs. Deducting the assay cost, estimated net savings of over €3.3 million were achieved. Changes in the ordering demographics of Oncotype DX tests were identified after RxPONDER data were presented, with increased testing in women ≥ 50 years and a reduction in proportion of tests ordered for women < 50 years.

CONCLUSION

Between 2011 and 2022, assay use resulted in a 58% reduction in chemotherapy administration and net savings of over €3.3 million.

Tailoring neoadjuvant systemic therapy in breast cancer: "The advent of a personalized approach"-The Breast-Gynecological and Immuno-Oncology International Cancer Conference (BGICC) consensus and recommendations

BACKGROUND

The management of early breast cancer (BC) has witnessed an uprise in the use of neoadjuvant therapy and a remarkable reshaping of the systemic therapy postneoadjuvant treatment in the last few years, with the evolution of many controversial clinical situations that require consensus.

METHODS

During the 14th Breast-Gynecological and Immuno-Oncology International Cancer Conference held in Egypt in 2022, a panel of 44 BC experts from 13 countries voted on statements concerning debatable challenges in the neo/adjuvant treatment setting. The recommendations were subsequently updated based on the most recent data emerging. A modified Delphi approach was used to develop this consensus. A consensus was achieved when ≥75% of voters selected an answer.

RESULTS AND CONCLUSIONS

The consensus recommendations addressed different escalation and de-escalation strategies in the setting of neoadjuvant therapy for early BC. The recommendations recapitulate the available clinical evidence and expert opinion to individualize patient management and optimize therapy outcomes. Consensus was reached in 63% of the statements (52/83), and the rationale behind each statement was clarified.

The impact of extensive intraductal component (EIC) on the genomic risk of recurrence in early hormone receptor positive breast cancer

BACKGROUND

Early invasive ductal carcinoma (IDC) breast cancer often presents with a coexisting ductal carcinoma in situ (DCIS) component, while about 5 % of cases present with an extensive (>25 %) intraductal component (EIC). The impact of EIC on the genomic risk of recurrence is unclear.

METHODS

Patients with early hormone receptor-positive HER2neu-negative (HR + HER2-) IDC breast cancer and a known OncotypeDX Breast Recurrence Score® (RS) who underwent breast surgery at our institute were included. Using a rule-based text-analysis algorithm, we analyzed pathological reports and categorized patients into three groups: EIC, non-extensive DCIS (DCIS-L), and pure-IDC (NO-DCIS). Genomic risk was determined using OncotypeDX RS.

RESULTS

A total of 33 (4.6 %) EIC cases, 377 (57.2 %) DCIS-L cases and 307 (42.8 %) NO-DCIS cases were identified. Patients in the EIC group were younger and had lower tumor grades than other groups. The distribution of genomic risk varied between the groups, with EIC tumors significantly less likely to have a high RS (>25) compared to DCIS-L and No-DCIS tumors (3 % vs 20 % and 20 %, respectively; p = 0.03). When adjusted to age, tumor size, grade and LNs involvement, both DCIS-L and NO-DCIS groups were significantly correlated with a higher probability of high RS compared to the EIC group (OR 12.3 and OR 13.1, respectively; p < 0.02). Moreover, patients with EIC had a lower likelihood for adjuvant chemotherapy recommendation.

CONCLUSIONS

In early HR + HER2- IDC, an EIC correlates with a reduced genomic recurrence risk. The impact on genomic risk seems to be influenced by the extent, not merely the presence, of DCIS.

Electronic Health Record-Based Nudge Intervention and Axillary Surgery in Older Women With Breast Cancer: A Nonrandomized Controlled Trial

Importance

Choosing Wisely recommendations advocate against routine use of axillary staging in older women with early-stage, clinically node-negative (cN0), hormone receptor-positive (HR+), and HER2-negative breast cancer. However, rates of sentinel lymph node biopsy (SLNB) in this population remain persistently high.

Objective

To evaluate whether an electronic health record (EHR)-based nudge intervention targeting surgeons in their first outpatient visit with patients meeting Choosing Wisely criteria decreases rates of SLNB.

Design, Setting, and Participants

This nonrandomized controlled trial was a hybrid type 1 effectiveness-implementation study with subsequent postintervention semistructured interviews and lasted from October 2021 to October 2023. Data came from EHRs at 8 outpatient clinics within an integrated health care system; participants included 7 breast surgical oncologists. Data were collected for female patients meeting Choosing Wisely criteria for omission of SLNB (aged ≥70 years with cT1 and cT2, cN0, HR+/HER2- breast cancer). The study included a 12-month preintervention control period; baseline surveys assessing perceived acceptability, appropriateness, and feasibility of the designed intervention; and a 12-month intervention period.

Intervention

A column nudge was embedded into the surgeon's schedule in the EHR identifying patients meeting Choosing Wisely criteria for potential SLNB omission.

Main Outcomes and Measures

The primary outcome was rate of SLNB following nudge deployment into the EHR.

Results

Similar baseline demographic and tumor characteristics were observed before (control period, n = 194) and after (intervention period, n = 193) nudge deployment. Patients in both the control and intervention period had a median (IQR) age of 75 (72-79) years. Compared with the control period, unadjusted rates of SLNB decreased by 23.1 percentage points (46.9% SLNB rate prenudge to 23.8% after; 95% CI, -32.9 to -13.8) in the intervention period. An interrupted time series model showed a reduction in the rate of SLNB following nudge deployment (adjusted odds ratio, 0.26; 95% CI, 0.07 to 0.90; P = .03). The participating surgeons scored the intervention highly on acceptability, appropriateness, and feasibility. Dominant themes from semistructured interviews indicated that the intervention helped remind the surgeons of potential Choosing Wisely applicability without the need for additional clicks or actions on the day of the patient visit, which facilitated use.

Conclusions and Relevance

This study showed that a nudge intervention in the EHR significantly decreased low-value axillary surgery in older women with early-stage, cN0, HR+/HER2- breast cancer. This user-friendly and easily implementable EHR-based intervention could be a beneficial approach for decreasing low-value care in other practice settings or patient populations.

Trial Registration

ClinicalTrials.gov Identifier: NCT06006910.

Contemporary Axillary Surgical Management in Patients with Pathologically Node Positive Disease After Neoadjuvant Chemotherapy: A Survey of Members of the American Society of Breast Surgeons

BACKGROUND

Axillary lymph node dissection (ALND) is increasingly omitted for breast cancer patients with pathologic nodal disease after neoadjuvant chemotherapy (NAC). This study aimed to understand when and why surgeons consider omitting ALND after NAC.

METHODS

The American Society of Breast Surgeons membership was surveyed, and responses were tabulated. To identify patterns, multiple correspondence analyses followed by cluster analysis on coordinates provided by the former were performed. Chi-squared analyses determined whether cluster characteristics were significantly (P < 0.05) associated with omission of ALND.

RESULTS

Of members, 328/2172 (15.1%) completed the survey. Most (60.7%) always offer sentinel lymph node surgery to cN1 patients who respond to NAC, and many (43.9%) sometimes omit ALND in the setting of residual nodal disease. Respondents less often consider omitting ALND with increasing volume of pathologic nodal disease after NAC and are less likely to omit ALND among patients with cN1 disease at presentation than cN0 (P < 0.05 across all volumes). Respondents cited radiation administration (74.1%) and belief that ALND would not improve locoregional (48.2%), distant recurrence or survival (47.6%) outcomes when axillary radiation is administered as reasons to omit ALND. The respondent group comprising male private practice surgeons, practicing ≥ 21 years, consider omitting ALND significantly more frequently.

CONCLUSIONS

Surgeons sometimes consider ALND omission for patients with pathologic nodal disease after NAC but are more likely to do so in cN0 patients and patients with smaller volumes of nodal disease. These decisions are largely based on perceived lack of oncologic benefit despite absence of prospective data supporting this deescalation.

Nodal Surgery for Patients ≥ 70 Undergoing Mastectomy for DCIS? Choose Wisely

BACKGROUND

Routine sentinel lymphadenectomy (SLNB) for early-stage HR+/HER2- breast cancer in women ≥70 is discouraged by Choosing Wisely, but whether SLNB can be routinely omitted in women ≥70 with DCIS undergoing mastectomy is unclear. This study aims to evaluate rates of axillary surgery and nodal positivity (pN+) in this population to determine the impact of axillary surgery on treatment decisions.

METHODS

Females ≥70 with DCIS undergoing mastectomy were identified from the National Cancer Database (2012-2020). The rate of upstaging to invasive cancer (≥pT1) or pN+ was assessed. Subset analyses were conducted for ER+ patients. Adjuvant therapies were evaluated among ≥pT1 patients after stratifying by nodal status.

RESULTS

Of 9,030 patients, 1,896 (21%) upstaged to ≥pT1. Axillary surgery was performed in 86% of patients, predominantly sentinel lymphadenectomy (SLNB, 65%). Post hoc application of Choosing Wisely criteria demonstrated that 93% of the entire cohort and 97% of ER+ DCIS patients could have avoided axillary surgery. Nodal positivity was 0.3% among those who didn't upstage, and 12% among those upstaging to ≥pT1, with <2% having pN2-3 disease, irrespective of receptor subtype. Node-positive patients had higher adjuvant therapy usage, but there was no recommendation for adjuvant chemotherapy or radiation for 71% and 66% of pN+ patients, respectively.

CONCLUSIONS

Axillary surgery can be omitted for most patients ≥70 undergoing mastectomy for ER+ DCIS, aligning with recommendations for invasive cancer, and omission can be considered in those with ER- disease. Future guidelines incorporating preoperative imaging, as in the SOUND trial, may aid in identifying patients benefiting from axillary surgery.

Correlating Predicted Adjuvant Therapy Benefit and Risk of Recurrence Between Breast Cancer Index (BCI) and the 21-Gene Oncotype DX Recurrence Score (RS)

INTRODUCTION

Breast Cancer Index (BCI) is a genomic assay that evaluates the benefit of extending endocrine therapy (ET) from 5 to 10 years and predicts recurrence risk (RR). We evaluated the association between BCI and Oncotype DX (ODX).

PATIENTS

Women with hormone receptor (HR)-positive early-stage breast cancer (EBC) who had BCI and ODX performed were included.

METHODS

We performed a retrospective review of women with HR-positive EBC. BCI was categorized as predictive of extended ET versus not and ODX recurrence score (RS) as low (0-10), intermediate (11-25), and high (26-100). Univariate and multivariable logistic and linear regression models assessed the relationship between BCI and ODX, factors associated with each, and discordance between scores.

RESULTS

We identified 153 women, 22% were premenopausal and 18% were lymph node positive. The univariate logistic and linear models revealed an association between BCI predictive score and ODX RS (OR 7.84, CI, 2.63-23.36, P < .001) and log of BCI RR (Beta 0.04, CI, 0.02-0.06, P < .001). Seventy-four percent of BCI predictive scores were concordant with ODX RS and 83% of BCI RR was concordant with ODX RR. In a univariate logistic regression model, BCI predictive of ET benefit was associated with discordance (OR 28.00, CI, 10.58-74.02, P < .001). Higher ODX RR was associated with discordance (OR 1.92, CI, 1.42-2.59, P < .001).

CONCLUSION

We found a significant association between ODX and BCI predictive and prognostic scores. BCI predictive of extended ET benefit was associated with discordance with ODX RS. Higher predicted RR on ODX was associated with discordance with BCI predicted RR.

Neoadjuvant letrozole and palbociclib in patients with HR-positive/HER2-negative early breast cancer and Oncotype DX Recurrence Score ≥18: DxCARTES study

BACKGROUND

The effect of the addition of cyclin-dependent kinases 4 and 6 inhibitors to endocrine therapy in terms of molecular downstaging remains undetermined. Switching from a high-risk to a low risk Recurrence Score (RS) group could provide useful information to identify patients who might not require chemotherapy. The purpose of this study was to assess the biological and clinical activity of letrozole plus palbociclib as neoadjuvant treatment for patients with hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative early breast cancer with an initial Oncotype DX RS ≥18.

PATIENTS AND METHODS

Participants were women aged ≥18 years with HR-positive/HER2-negative, Ki67 ≥ 20%, stage II-IIIB early breast cancer with a baseline RS ≥18. Eligible patients with a pretreatment RS 18-25 (cohort A) and 26-100 (cohort B) received six 28-day cycles of letrozole (2.5 mg per day; plus goserelin if pre- or perimenopausal) plus palbociclib (125 mg per day; 3/1 schedule) before surgery. The primary endpoint for both cohorts was the proportion of patients who achieved an RS ≤25 at surgery or a pathological complete response (pCR).

RESULTS

A total of 67 patients were enrolled, among which 65 were assessable for the primary endpoint (32 patients in cohort A and 33 in cohort B). At surgery, 22 (68.8%) patients in cohort A and 18 (54.5%) patients in cohort B had an RS ≤25 or a pCR [only 1 (3.0%) patient in cohort B], meeting the primary endpoint in cohort B (P < 0.01), but not in cohort A (P = 0.98). No new safety signals were identified.

CONCLUSIONS

The efficacy of neoadjuvant treatment with letrozole plus palbociclib does not seem to depend on pretreatment RS for patients with RS ≥18. However, around half of patients with HR-positive/HER2-negative early breast cancer with an RS 26-100 at baseline achieved molecular downstaging with this regimen.

Prediction of High Nodal Burden in Patients With Sentinel Node-Positive Luminal ERBB2-Negative Breast Cancer

Importance

In patients with clinically node-negative (cN0) breast cancer and 1 or 2 sentinel lymph node (SLN) macrometastases, omitting completion axillary lymph node dissection (CALND) is standard. High nodal burden (≥4 axillary nodal metastases) is an indication for intensified treatment in luminal breast cancer; hence, abstaining from CALND may result in undertreatment.

Objective

To develop a prediction model for high nodal burden in luminal ERBB2-negative breast cancer (all histologic types and lobular breast cancer separately) without CALND.

Design, Setting, and Participants

The prospective Sentinel Node Biopsy in Breast Cancer: Omission of Axillary Clearance After Macrometastases (SENOMAC) trial randomized patients 1:1 to CALND or its omission from January 2015 to December 2021 among adult patients with cN0 T1-T3 breast cancer and 1 or 2 SLN macrometastases across 5 European countries. The cohort was randomly split into training (80%) and test (20%) sets, with equal proportions of high nodal burden. Prediction models were developed by multivariable logistic regression in the complete luminal ERBB2-negative cohort and a lobular breast cancer subgroup. Nomograms were constructed. The present diagnostic/prognostic study presents the results of a prespecified secondary analysis of the SENOMAC trial. Herein, only patients with luminal ERBB2-negative tumors assigned to CALND were selected. Data analysis for this article took place from June 2023 to April 2024.

Exposure

Predictors of high nodal burden.

Main Outcomes and Measures

High nodal burden was defined as ≥4 axillary nodal metastases. The luminal prediction model was evaluated regarding discrimination and calibration.

Results

Of 1010 patients (median [range] age, 61 [34-90] years; 1006 [99.6%] female and 4 [0.4%] male), 138 (13.7%) had a high nodal burden and 212 (21.0%) had lobular breast cancer. The model in the training set (n = 804) included number of SLN macrometastases, presence of SLN micrometastases, SLN ratio, presence of SLN extracapsular extension, and tumor size (not included in lobular subgroup). Upon validation in the test set (n = 201), the area under the receiver operating characteristic curve (AUC) was 0.74 (95% CI, 0.62-0.85) and the calibration was satisfactory. At a sensitivity threshold of ≥80%, all but 5 low-risk patients were correctly classified corresponding to a negative predictive value of 94%. The prediction model for the lobular subgroup reached an AUC of 0.74 (95% CI, 0.66-0.83).

Conclusions and Relevance

The predictive models and nomograms may facilitate systemic treatment decisions without exposing patients to the risk of arm morbidity due to CALND. External validation is needed.

Trial Registration

ClinicalTrials.gov Identifier: NCT02240472.

Spatial oncology: Translating contextual biology to the clinic

Microscopic examination of cells in their tissue context has been the driving force behind diagnostic histopathology over the past two centuries. Recently, the rise of advanced molecular biomarkers identified through single cell profiling has increased our understanding of cellular heterogeneity in cancer but have yet to significantly impact clinical care. Spatial technologies integrating molecular profiling with microenvironmental features are poised to bridge this translational gap by providing critical in situ context for understanding cellular interactions and organization. Here, we review how spatial tools have been used to study tumor ecosystems and their clinical applications. We detail findings in cell-cell interactions, microenvironment composition, and tissue remodeling for immune evasion and therapeutic resistance. Additionally, we highlight the emerging role of multi-omic spatial profiling for characterizing clinically relevant features including perineural invasion, tertiary lymphoid structures, and the tumor-stroma interface. Finally, we explore strategies for clinical integration and their augmentation of therapeutic and diagnostic approaches.

21-gene recurrence score predictive of the benefit of postoperative radiotherapy after breast-conserving surgery for elderly patients with T1N0 and luminal breast cancer

PURPOSE

To assess the predictive value of the 21-gene recurrence score (RS) on the survival outcomes of postoperative radiotherapy (PORT) in elderly patients with T1N0 luminal breast cancer after breast-conserving surgery.

METHODS

We retrospectively included patients aged ≥ 70 years and diagnosed with T1N0 luminal BC between 2004 and 2015 using the data from the Surveillance, Epidemiology, and End Results. The RS groups were categorized using the TAILORx criteria as follows: low risk (RS < 11) (LR), intermediate risk (RS 11-25) (IR), and high risk (RS > 25) (HR). Kaplan-Meier analysis, propensity score matching (PSM), and Cox proportional hazards analysis were used for statistical analysis.

RESULTS

We included 5901 patients in the analysis. Of the patients, 4492 (76.1%) underwent PORT, while 1409 (23.9%) did not receive PORT. There were 1588 (26.9%), 3613 (61.2%), and 700 (12.0%) patients classified as LR, IR, and HR, respectively. There were 1182 (74.4%), 2773 (76.8%), and 537 (76.7%) patients in the LR, IR, and HR groups receiving PORT, respectively (P = 0.182). A total of 1353 pairs of patients were completely matched using PSM. PORT was independently associated with better overall survival (OS) (P < 0.001) and breast cancer-specific survival (BCSS) (P = 0.015) in the entire cohort. The sensitivity analyses showed that the receipt of PORT was not associated with OS (P = 0.887) and BCSS (P = 0.861) in the LR group. However, the receipt of PORT was associated with OS (P < 0.001) and BCSS in the IRHR group (P = 0.026).

CONCLUSION

Our study highlights the possible role of the 21-gene RS in predicting the survival outcomes of PORT following BCS in elderly patients with T1N0 luminal breast cancer.

Incidence of Pathologic Nodal Disease in Clinically Node-Negative, Microinvasive or T1a Breast Cancers

BACKGROUND

Axillary staging in early-stage breast cancer can impact adjuvant treatment options but also has associated morbidity. The incidence of pathologic nodal positivity (pN+) in patients with microinvasive or T1a disease is poorly characterized and the value of sentinel node biopsy remains controversial.

METHODS

Women with cN0 and pathologic microinvasive or T1a cancer who underwent upfront surgery were identified from the National Cancer Database. Pathologic nodal stage at the time of surgery was the primary outcome. Multivariable logistic modeling was used to assess predictors of pN+.

RESULTS

Overall, 141,840 women were included; 139,206 had pathologic node-negative (pN0) disease and 2634 had pN+ disease. Rates of pN+ disease differed by receptor status, with the highest rates in hormone receptor-negative/human epidermal growth factor receptor 2-positive (HR-/HER2+) disease compared with triple-negative breast cancer (TNBC), HR-positive/HER2-negative (HR+/HER2-), and triple positive breast cancer. Rates of pN+ were also higher with lobular histology compared with ductal histology. Multivariable analysis demonstrated that compared with White women, Black women had higher odds of pN+ disease, and compared with women <50 years of age, women >70 years of age had higher odds of pN+ disease. Compared with women with HR+/HER2- disease, women with TNBC, triple-positive breast cancer, and HR-/HER2+ all had lower odds, and women with invasive lobular disease had higher odds compared with women with invasive ductal disease. Women with significant comorbidities also had higher odds of node positivity.

CONCLUSION

Over 90% of patients with clinically node-negative, microinvasive and T1a breast cancer remain pathologically node-negative following axillary staging. However, higher rates of nodal disease were found among Black patients, older patients, and patients with lobular cancer and significant comorbidities.

Hormone receptor-positive early breast cancer in young women: A comprehensive review

The incidence of breast cancer in ≤ 40 yr-old women (YWBC) has been steadily increasing in recent decades. Although this group of patients represents less than 10 % of all newly diagnosed BC cases it encompasses a significant burden of disease. Usually underrepresented in clinical trials, YWBCs are also characterized by late diagnoses and poorly differentiated, aggressive-subtype disease, partly explaining its poor prognosis along with a high recurrence risk, and high mortality rates. On the other hand, YWBC treatment poses unique challenges such as preservation of fertility, and long-term toxicity and adverse events. Herein, we summarize the current evidence in hormone receptor-positive YWBC including specific risk factors, clinicopathologic and genomic features, and available evidence on response to chemotherapy and endocrine therapy. Overall, we advocate for a more comprehensive multidisciplinary healthcare model to improve the outcomes and the quality of life of this subset of younger patients.

The REMAR (Rhein-Main-Registry) real-world study: prospective evaluation of the 21-gene breast recurrence score® assay in addition to Ki-67 for adjuvant treatment decisions in early-stage breast cancer

PURPOSE

Ki-67 is recommended by international/national guidelines for risk stratification in early breast cancer (EBC), particularly for defining "intermediate risk," despite inter-laboratory/inter-observer variability and cutoff uncertainty. We investigated Ki-67 (> 10%- < 40%, determined locally) as a prognostic marker for intermediate/high risk in EBC, pN0-1 patients.

METHODS

This prospective, non-interventional, real-world study included females ≥ 18 years, with pN0/pN1mi/pN1, HR+ , HER2-negative EBC, and locally determined Ki-67 ranging 10%-40%. The primary outcome was changes in treatment recommendations after disclosing the Oncotype DX Breast Recurrence Score®(RS) assay result.

RESULTS

The analysis included 567 patients (median age, 57 [range, 29-83] years; 70%/1%/29%/ with pN0/pN1mi/pN1 disease; 81% and 19% with RS results 0-25 and 26-100, respectively). The correlations between local and central Ki-67, local Ki-67, and the RS, and central Ki-67 and the RS results were weak (r = 0.35, r = 0.3, and r = 0.46, respectively), and discrepancies were noted in both directions (e.g., local Ki-67 was lower or higher than central Ki-67). After disclosing the RS, treatment recommendations changed for 190 patients (34%). Changes were observed in pN0 and pN1mi/pN1 patients and in patients with centrally determined Ki-67 ≤ 10% and > 10%. Treatment changes were aligned with RS results (adding chemotherapy for patients with higher RS results, omitting it for lower RS results), and their net result was 8% reduction in adjuvant chemotherapy use (from 32% pre-RS results to 24% post-RS results).

CONCLUSION

The Oncotype DX® assay is a tool for individualizing treatments that adds to classic treatment decision factors. The RS result and Ki-67 are not interchangeable, and Ki-67, as well as nodal status, should not be used as gatekeepers for testing eligibility, to avoid under and overtreatment.

Phase III Randomized, Placebo-Controlled Trial of Endocrine Therapy ± 1 Year of Everolimus in Patients With High-Risk, Hormone Receptor-Positive, Early-Stage Breast Cancer

PURPOSE

Phosphatidylinositol 3-kinase/AKT-serine threonine kinase/mammalian target of rapamycin (mTOR) pathway abnormalities contribute to endocrine resistance. Everolimus, an mTOR inhibitor, improved progression-free survival in hormone receptor-positive metastatic breast cancer (BC) when combined with endocrine therapy (ET). In this phase III randomized, placebo-controlled trial, we assessed the efficacy of everolimus + ET as adjuvant therapy in high-risk, hormone receptor-positive, human epidermal growth factor receptor 2-negative BC after adjuvant/neoadjuvant chemotherapy.

METHODS

Patients were randomly assigned 1:1 to physician's choice ET and 1 year of everolimus (10 mg orally once daily) or placebo stratified by risk group. The primary end point was invasive disease-free survival (IDFS) evaluated by a stratified log-rank test with the hazard ratio (HR) estimated by Cox regression. Subset analyses included preplanned evaluation by risk group and exploratory analyses by menopausal status and age. Secondary end points included overall survival (OS) and safety. Everolimus did not improve IDFS/OS when added to ET in patients with early-stage high-risk, hormone receptor-positive BC.

RESULTS

One thousand and nine hundred thirty-nine patients were randomly assigned with 1,792 eligible for analysis. Overall, no benefit of everolimus was seen for IDFS (HR, 0.94 [95% CI, 0.77 to 1.14]) or OS (HR, 0.97 [95% CI, 0.75 to 1.26]). The assumption of proportional hazards was not met suggesting significant variability in the HR over time since the start of treatment. In an unplanned subgroup analysis among postmenopausal patients (N = 1,221), no difference in IDFS (HR, 1.08 [95% CI, 0.86 to 1.36]) or OS (HR, 1.19 [95% CI, 0.89 to 1.60]) was seen. In premenopausal patients (N = 571), everolimus improved both IDFS (HR, 0.64 [95% CI, 0.44 to 0.94]) and OS (HR, 0.49 [95% CI, 0.28 to 0.86]). Treatment completion rates were lower in the everolimus arm compared with placebo (48% v 73%) with higher grade 3 and 4 adverse events (35% v 7%).

CONCLUSION

One year of adjuvant everolimus + ET did not improve overall outcomes. Subset analysis suggests mTOR inhibition as a possible target for patients who remain premenopausal after chemotherapy.

Association of Oncotype-DX HER2 Single Gene Score With HER2 Expression Assessed by Immunohistochemistry in HER2-low Breast Cancer

Background/Aim

"HER2-low" is an emerging subtype of breast cancer, with a documented role in predicting response to treatment with novel antibody-drug conjugates. It is defined based on immunohistochemistry, but increasing evidence is challenging this approach as appropriate for identifying the HER2-low subgroup, due to both interobserver variability and limitations of the method itself.

Patients and Methods

We retrospectively analyzed data from 430 patients from our departmental databases who had been subjected to an Oncotype-DX score and assessed the correlation of the Oncotype-DX HER2 single-gene score with the HER2 expression on immunohistochemistry. The Oncotype-DX Recurrence Score was also evaluated in the HER2-0 versus HER2-low subgroups.

Results

The HER2 single-gene score was found to accurately correlate with the HER2 result on immunohistochemistry, with a statistically significant difference both between HER2-0 and HER2 +1 tumors (p<0.0001), as well as between HER2 +1 and +2 tumors (p<0.0001). There was no statistically significant difference in the recurrence score between the HER2-0 and the HER2-low subgroups.

Conclusion

Oncotype-DX single-gene scores for HER2 are a potential surrogate marker for assessing the precise HER2 status, with better reproducibility and less interobserver variance compared to immunohistochemistry. The use of rt-PCR emerges as an alternative method of assessment of the HER2-low subgroup.

Revisiting ovarian function suppression with GnRH agonists for premenopausal women with breast cancer: Who should use and the impact on survival outcomes

Breast cancer diagnosed in premenopausal women tends to be more aggressive and the benefit of ovarian function suppression (OFS), at least in certain groups of patients, is well known. There is hesitancy in using OFS in some groups of patients who may otherwise benefit from the treatment. For instance, it is clear that in premenopausal patients with hormone receptor-positive (HR+), high-risk, early-stage breast cancer, gonadotropin-releasing hormone agonists (GnRHa) should be given in the adjuvant setting; however, confusion remains whether premenopausal patients with intermediate-risk disease benefit from GnRHa, given the lack of consensus on its definition in guidelines and clinical practice. Most recent evidence on the long-term efficacy of GnRHa, with up to 20-years of follow-up, reinforced its benefits in premenopausal patients with early-stage breast cancer. In this comprehensive review, we reviewed the long-term efficacy in terms of improvement in disease-free survival (DFS) and overall survival (OS) for early-stage HR+ breast cancer and examined evidence from multiple randomized clinical studies to identify the clinicopathological characteristics that correlated with improved DFS and OS with the addition of OFS to adjuvant endocrine therapy. Other aspects of GnRHa, including its efficacy in advanced breast cancer, safety profile, evidence in ovarian function preservation, and the advantages of long-acting formulations were also discussed. By addressing the existing gaps and grey areas regarding the inclusion of OFS as a crucial treatment component for premenopausal breast cancer patients, physicians are more aware of who to administer and the potential impact on survival outcomes.

Neoadjuvant Therapy: Current Landscape and Future Horizons for ER-Positive/HER2-Negative and Triple-Negative Early Breast Cancer

OPINION STATEMENT

Navigating the complex landscape of breast cancer treatment involves distinct strategies for luminal and triple-negative subtypes. While neoadjuvant chemotherapy historically dominates the approach for aggressive triple-negative tumors, recent evidence highlights the transformative impact of immunotherapy, alongside chemotherapy, in reshaping treatment paradigms. In luminal cancers, endocrine therapy, notably aromatase inhibitors, demonstrates promising outcomes in postmenopausal patients with low-grade luminal A tumors. However, integrating targeted therapies like CDK4/6 inhibitors in neoadjuvant setting remains inconclusive. Identifying predictive factors for treatment response, especially in luminal tumors, poses a challenge, emphasizing the necessity for ongoing research. A multidisciplinary approach, tailored to individual patient profiles, is crucial for maximizing efficacy while minimizing toxicity. As we strive to optimize breast cancer management, a comprehensive understanding of the distinct characteristics and treatment implications of luminal and triple-negative subtypes, including the transformative role of immunotherapy, is essential for informed decision-making and personalized care.

Omission of axillary surgery in cN0, postmenopausal ER-positive/HER2-negative breast cancer patients undergoing breast-conserving treatment

Background

Previous clinical trials have diminished the significance of lymph node (LN) metastasis and axillary surgery in breast cancer, particularly in cN0, postmenopausal estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative patients undergoing breast-conserving treatment (BCT). We assessed the replacement of axillary surgery with preoperative imaging modalities by analyzing the proportion of high nodal burden (HNB) patients with ≥3 LN metastases in these patients.

Methods

We retrospectively identified 333 cN0, postmenopausal ER-positive/HER2-negative breast cancer patients who underwent BCT in two hospitals between January 2003 and December 2017. The proportion of LN metastasis patients and the number of metastatic LN were investigated. Risk factors of LN metastasis were analyzed and recurrence-free survival (RFS) was compared.

Results

Axillary surgery confirmed LN metastasis in 81 (24.3%) of the cN0 patients. The clinical tumor size (cT) and age were factors associated with LN metastasis [cT: odds ratio (OR), 2.92, 95% confidence interval (CI): 1.69-5.05, P<0.001; age: OR, 0.33, 95% CI: 0.11-0.99, P=0.048]. However, HNB patients with ≥3 LN metastases were 15 (4.5%) of all the patients. There was statistically significant difference in the incidence of HNB between patients with cT1 tumors (3.6%) and those with cT2 tumors (7.4%) (P<0.001).

Conclusions

In cN0, postmenopausal ER-positive/HER2-negative patients who underwent BCT, patients with cT1 tumors had lower rate of LN metastasis, and there were fewer instances of HNB. Therefore, in these patients, omission of axillary surgery including SLNB can be carefully considered.

Real-World Analysis of Breast Cancer Patients Qualifying for Adjuvant CDK4/6 Inhibitors

BACKGROUND

Adjuvant CDK4/6 inhibitors abemaciclib and ribociclib improved disease-free survival (DFS) added to endocrine therapy in hormone receptor (HR)-positive HER2-negative early breast cancer (EBC), in monarchE (NCT03155997) and NATALEE (NCT03701334) trials respectively. We assessed the proportion and outcome of EBC patients qualifying for adjuvant CDK4/6 inhibitors in the real-world.

METHODS

Consecutive female patients with HR-positive HER2-negative EBC between 1997 and 2017 from the Australian Capital Territory and South-East New South Wales Breast Cancer Treatment Group registry were analyzed. Patients eligible for abemaciclib had ≥4 axillary nodes involved or 1-3 nodes plus primary >5 cm or grade 3. Ribociclib eligibility was defined as node-positive and node-negative with primary >5 cm or >2 cm grade 3.

RESULTS

Of 3840 patients, 671 (17.5%) were abemaciclib-eligible and 1587 (41.3%) ribociclib-eligible . The 5-year DFS was 77% and 94% in abemaciclib-eligible and noneligible registry patients respectively (HR 2.6, 95% CI 2.26-3.05, P < .001). The 5-year DFS was 86% and 97% in ribociclib-eligible and noneligible registry patients respectively (HR 1.92, 95% CI 1.67-2.19, P < .001). Compared with monarchE trial patients, abemaciclib-eligible registry patients were older (median 55 years in registry vs. 51 years in trial), with lower nodal burden (≥4 nodes in 44% in registry vs. 60% in trial). There were more stage III cancers in NATALEE trial patients (60%) than ribociclib-eligible registry patients (24%).

CONCLUSIONS

Many women with EBC will qualify for adjuvant CDK4/6 inhibitors (17.5% abemaciclib, 41.3% ribociclib) with resource and workforce implications. In the real-world setting, a greater proportion of adjuvant CDK4/6-eligible patients have lower stage disease, therefore the absolute benefit from treatment may be smaller than estimated by the trials.

How to Tackle Discordance in Adjuvant Chemotherapy Recommendations by Using Oncotype DX Results, in Early-Stage Breast Cancer

BACKGROUND

The use of the Oncotype DX test reduces the rate of adjuvant chemotherapy recommendations. Few in-depth analyses have been performed on this decision-making process.

METHODS

We retrospectively analyzed patient data based on available Oncotype DX test results (RS) irrespective of nodal status at a single center. We collected recommendations from six oncologists, first without RS (pre-RS) and then with RS results (post-RS). We investigated changes in recommendations, agreement between oncologist decisions, and the effect of different National Comprehensive Cancer Network (NCCN) recommendation categories (for, against, and considering chemotherapy).

RESULTS

Data from 201 patients were included in the analysis. Recommendation of chemotherapy decreased by an average of 39.5%. Agreement improved substantially with RS, with a kappa value pre-RS of 0.37 (fair agreement) and post-RS of 0.75 (substantial agreement). Discordance remained substantial in cases where the NCCN recommendations considered chemotherapy only (32%). Pre-RS consensus against chemotherapy predicted low RS results (50 out of 51 patients). Post-RS consensus was highest in the NCCN chemotherapy recommendation group.

CONCLUSIONS

The Oncotype DX test substantially improves decision accuracy in recommending adjuvant chemotherapy. It may be further improved with a consensus decision. In the case of pre-RS consensus against chemotherapy, the test can be spared.

Current status and future perspectives of contrast-enhanced ultrasound diagnosis of breast lesions

Advances in various imaging modalities for breast lesions have improved diagnostic capabilities not only for tumors but also for non-tumorous lesions. Contrast-enhanced ultrasound (CEUS) plays a crucial role not only in the differential diagnosis of breast lesions, identification of sentinel lymph nodes, and diagnosis of lymph node metastasis but also in assessing the therapeutic effects of neoadjuvant chemotherapy (NAC). In CEUS, two image interpretation approaches, i.e., qualitative analysis and quantitative analysis, are employed and applied in various clinical settings. In this paper, we review CEUS for breast lesions, including its various applications.

Impact of Molecular Profiling on Therapy Management in Breast Cancer

Breast cancer (BC) remains the most prevalent cancer among women and the leading cause of cancer-related mortality worldwide. The heterogeneity of BC in terms of histopathological features, genetic polymorphisms, and response to therapies necessitates a personalized approach to treatment. This review focuses on the impact of molecular profiling on therapy management in breast cancer, emphasizing recent advancements in next-generation sequencing (NGS) and liquid biopsies. These technologies enable the identification of specific molecular subtypes and the detection of blood-based biomarkers such as circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and tumor-educated platelets (TEPs). The integration of molecular profiling with traditional clinical and pathological data allows for more tailored and effective treatment strategies, improving patient outcomes. This review also discusses the current challenges and prospects of implementing personalized cancer therapy, highlighting the potential of molecular profiling to revolutionize BC management through more precise prognostic and therapeutic interventions.

Long-Term Survival Outcomes and Risk Factors for Axillary and Locoregional Recurrence in Japanese Patients with Sentinel Node-Positive Breast Cancer Treated in Accordance with the ACOSOG Z0011 Strategy

INTRODUCTION

In 2018, we reported the results of a study to assess the feasibility of applying the ACOSOG Z0011 criteria to Japanese patients with early-stage breast cancer (median follow-up, 3 years). Their results over the longer term can now be presented. Risk factors for axillary and locoregional recurrence in Z0011-eligible patients are unknown.

METHODS

Long-term survival outcomes were investigated by analyzing data from patients enrolled in the feasibility study. Data from the feasibility study patients, and from patients eligible for the Z0011 strategy after its introduction into clinical practice, were subjected to multivariate logistic regression analysis to identify risk factors for axillary and locoregional recurrence.

RESULTS

Regarding long-term outcomes for the feasibility study patients (n = 189), distant disease-free survival rates at 5 and 7 years were 90.4 ± 2.1% and 85.9 ± 2.6%, respectively, and overall survival rates at 5 and 7 years were 97.3 ± 1.2% and 95.3 ± 1.7%, respectively. Analysis of data from these patients plus the 93 who received Z0011 in clinical practice (total, n = 282) identified the following independent risk factors for axillary recurrence: absence of high axillary tangential irradiation (OR, 5.87 [95% CI, 1.09-31.35], p = 0.04) and number of positive sentinel lymph nodes (OR, 4.65 [95% CI, 1.11-19.48], p = 0.04). Only high Ki67 labeling index (OR, 5.92 [95% CI, 1.31-26.70], p = 0.02) was identified as an independent risk factor for locoregional recurrence.

CONCLUSION

Long-term survival outcome results of the feasibility study show that the Z0011 strategy can be used to treat Japanese patients with early-stage breast cancer. Our findings regarding risk factors suggest that high axillary tangent irradiation is necessary for the prevention of axillary recurrence and that irradiation, including of the regional lymph nodes, should be considered, especially in patients with high Ki67 index values.

Characterization of HER2-low breast cancer in young women with germline BRCA1/2 pathogenetic variants: Results of a large international retrospective cohort study

BACKGROUND

Breast cancer (BC) in women aged ≤40 years carrying germline pathogenetic variants (PVs) in BRCA1/2 genes is infrequent but often associated with aggressive features. Human epidermal growth factor receptor 2 (HER2)-low-expressing BC has recently emerged as a novel therapeutic target but has not been characterized in this rare patient subset.

METHODS

Women aged ≤40 years with newly diagnosed early-stage HER2-negative BC (HER2-0 and HER2-low) and germline BRCA1/2 PVs from 78 health care centers worldwide were retrospectively included. Chi-square test and Student t-test were used to describe variable distribution between HER2-0 and HER2-low. Associations with HER2-low status were assessed with logistic regression. Kaplan-Meier method and Cox regression analysis were used to assess disease-free survival (DFS) and overall survival. Statistical significance was considered for p ≤ .05.

RESULTS

Of 3547 included patients, 32.3% had HER2-low BC, representing 46.3% of hormone receptor-positive and 21.3% of triple-negative (TN) tumors. HER2-low vs. HER2-0 BC were more often of grade 1/2 (p < .001), hormone receptor-positive (p < .001), and node-positive (p = .003). BRCA2 PVs were more often associated with HER2-low than BRCA1 PVs (p < .001). HER2-low versus HER2-0 showed better DFS (hazard ratio [HR], 0.86; 95% CI, 0.76-0.97) in the overall population and more favorable DFS (HR, 0.78; 95% CI, 0.64-0.95) and overall survival (HR, 0.65; 95% CI, 0.46-0.93) in the TN subgroup. Luminal A-like tumors in HER2-low (p = .014) and TN and luminal A-like in HER2-0 (p = .019) showed the worst DFS.

CONCLUSIONS

In young patients with HER2-negative BC and germline BRCA1/2 PVs, HER2-low disease was less frequent than expected and more frequently linked to BRCA2 PVs and associated with luminal-like disease. HER2-low status was associated with a modestly improved prognosis.

Breast Cancer Index in Premenopausal Women With Early-Stage Hormone Receptor-Positive Breast Cancer

Importance

Adjuvant ovarian function suppression (OFS) with oral endocrine therapy improves outcomes for premenopausal patients with hormone receptor-positive (HR+) breast cancer but adds adverse effects. A genomic biomarker for selecting patients most likely to benefit from OFS-based treatment is lacking.

Objective

To assess the predictive and prognostic performance of the Breast Cancer Index (BCI) for OFS benefit in premenopausal women with HR+ breast cancer.

Design, Setting, and Participants

This prospective-retrospective translational study used all available tumor tissue samples from female patients from the Suppression of Ovarian Function Trial (SOFT). These individuals were randomized to receive 5 years of adjuvant tamoxifen alone, tamoxifen plus OFS, or exemestane plus OFS. BCI testing was performed blinded to clinical data and outcome. The a priori hypothesis was that BCI HOXB13/IL17BR ratio (BCI[H/I])-high tumors would benefit more from OFS and high BCI portended poorer prognosis in this population. Settings spanned multiple centers internationally. Participants included premenopausal female patients with HR+ early breast cancer with specimens in the International Breast Cancer Study Group tumor repository available for RNA extraction. Data were collected from December 2003 to April 2021 and were analyzed from May 2022 to October 2022.

Main Outcomes and Measures

Primary end points were breast cancer-free interval (BCFI) for the predictive analysis and distant recurrence-free interval (DRFI) for the prognostic analyses.

Results

Tumor specimens were available for 1718 of the 3047 female patients in the SOFT intention-to-treat population. The 1687 patients (98.2%) who had specimens that yielded sufficient RNA for BCI testing represented the parent trial population. The median (IQR) follow-up time was 12 (10.5-13.4) years, and 512 patients (30.3%) were younger than 40 years. Tumors were BCI(H/I)-low for 972 patients (57.6%) and BCI(H/I)-high for 715 patients (42.4%). Patients with tumors classified as BCI(H/I)-low exhibited a 12-year absolute benefit in BCFI of 11.6% from exemestane plus OFS (hazard ratio [HR], 0.48 [95% CI, 0.33-0.71]) and an absolute benefit of 7.3% from tamoxifen plus OFS (HR, 0.69 [95% CI, 0.48-0.97]) relative to tamoxifen alone. In contrast, patients with BCI(H/I)-high tumors did not benefit from either exemestane plus OFS (absolute benefit, -0.4%; HR, 1.03 [95% CI, 0.70-1.53]; P for interaction = .006) or tamoxifen plus OFS (absolute benefit, -1.2%; HR, 1.05 [95% CI, 0.72-1.54]; P for interaction = .11) compared with tamoxifen alone. BCI continuous index was significantly prognostic in the N0 subgroup for DRFI (n = 1110; P = .004), with 12-year DRFI of 95.9%, 90.8%, and 86.3% in BCI low-risk, intermediate-risk, and high-risk N0 cancers, respectively.

Conclusions and Relevance

In this prospective-retrospective translational study of patients enrolled in SOFT, BCI was confirmed as prognostic in premenopausal women with HR+ breast cancer. The benefit from OFS-containing adjuvant endocrine therapy was greater for patients with BCI(H/I)-low tumors than BCI(H/I)-high tumors. BCI(H/I)-low status may identify premenopausal patients who are likely to benefit from this more intensive endocrine therapy.

The population-level effects of omitting chemotherapy guided by a 21-gene expression assay in node-positive breast cancer: a simulation modeling study

BACKGROUND

A recent trial showed that postmenopausal women diagnosed with hormone receptor-positive, human epidermal growth factor receptor-2 (HER2)-negative, lymph node-positive (1-3 nodes) breast cancer with a 21-gene recurrence score of ≤ 25 could safely omit chemotherapy. However, there are limited data on population-level long-term outcomes associated with omitting chemotherapy among diverse women seen in real-world practice.

METHODS

We adapted an established, validated simulation model to generate the joint distributions of population-level characteristics of women diagnosed with early-stage breast cancer in the U.S. Input parameters were derived from cancer registry, meta-analyses, and clinical trial data. The effects of omitting chemotherapy on 10-year distant recurrence-free survival, life-years, and quality adjusted life-years (QALYs) were modeled for premenopausal and postmenopausal women. QALYs were discounted at 3%. Results were evaluated for subgroups stratified by race and ethnicity. Sensitivity analyses included testing results across a range of inputs. The model was validated using the published RxPONDER trial data.

RESULTS

In premenopausal women, the 10-year distant recurrence-free survival rates were 85.3% with chemo-endocrine and 80.1% with endocrine therapy. The estimated life-years and QALYs gained with chemotherapy in premenopausal women were 2.1 and 0.6, respectively. There was no chemotherapy benefit in postmenopausal women. There was no variation in the absolute benefit of chemotherapy across racial or ethnic subgroups. However, there were differences in distant recurrence-free survival rates, life-years, and QALYs across groups. Sensitivity analysis showed similar results. The model closely replicated the RxPONDER trial.

CONCLUSIONS

Modeled population-level outcomes show a small chemotherapy benefit in premenopausal women, but no benefit among postmenopausal women. Simulation modeling provides a useful tool to extend trial data and evaluate population-level outcomes.

Impact of Sentinel Lymph Node Biopsy on Management of Older Women With Clinically Node-Negative, Early-Stage, ER+/HER2-, Invasive Breast Cancer: A Systematic Review and Meta-Analysis

In 2016 the Choosing Wisely guidelines advised against routine performance of a sentinel lymph node biopsy (SLNB) in women ≥ 70 years of age with clinically node negative (cN0), early-stage, oestrogen receptor positive/ human epidermal growth factor receptor 2 negative (ER+/HER2-), invasive breast cancer. The argument in favour of its continued performance is that it may serve as a useful guide for subsequent management. This systematic review was performed in accordance with the PRISMA guidelines. Studies reporting on rate of adjuvant chemotherapy, adjuvant radiotherapy and performance of completion axillary lymph node dissection (cALND) post SLNB in women aged ≥ 65 years with cN0, early-stage, ER+/HER2-, invasive breast cancer were included. A random effects meta-analysis was performed with summary estimates made using the Mantel-Haenszel method. Dichotomous outcomes were reported as odds ratios (ORs) with 95% confidence intervals (CIs). Ten retrospective studies across 4 countries. Of 105,514 patients, 15,509 had a positive SLNB and 90,005 had a negative SLNB. On meta-analysis, a positive SLNB was significantly associated with receipt of adjuvant chemotherapy (OR 4.64 (95% CI 3.18, 6.77), P < .00001), adjuvant radiotherapy (1.71 (95% CI 1.18, 2.47), P = .005) and undergoing completion axillary lymph node dissection (OR 68.97 (95% CI, 7.47, 636.88), P = .0002). Adjuvant treatment decisions continue to be influenced by SLNB positivity in the era of the Choosing Wisely guidelines. The effects of a positive SLNB and subsequent treatments on outcomes remain inconclusive. However, it is likely clinicians are continuing to over-investigate and over-treat this cohort.

The Omission of Anthracycline Chemotherapy in Women with Early HER2-Negative Breast Cancer-A Systematic Review and Meta-Analysis

BACKGROUND

Anthracycline-taxane is the standard chemotherapy strategy for treating high-risk early breast cancer despite the potentially life-threatening adverse events caused by anthracyclines. Commonly, the combination of docetaxel and cyclophosphamide (TC) is considered an alternative option. However, the efficacy of TC compared to anthracycline-taxane chemotherapy is unclear. This study compares disease-free survival (DFS), overall survival (OS) and cardiotoxicity between adjuvant TC and anthracycline-taxane for stages I-III, HER2-negative breast cancer.

METHODS

A systematic search on MEDLINE, Embase and Cochrane CENTRAL for randomized-controlled trials published until 11 March 2024, yielded 203 studies with 11,803 patients, and seven trials were included.

RESULTS

TC results in little to no difference in DFS (HR 1.09, 95% CI 0.98-1.20; moderate-certainty of evidence); OS (1.02, 95% CI 0.89-1.16; high-certainty of evidence); and cardiotoxicity (RR 0.54, 95% CI 0.16-1.76; high-certainty of evidence), compared to anthracycline-taxane. In the subgroup analysis, patients with ≥4 lymph nodes had improved DFS from anthracycline-taxane over TC.

CONCLUSIONS

Overall, there was no difference between TC and anthracycline-taxane in DFS, OS and cardiotoxicity. In women with ≥4 nodes, anthracycline-taxane was associated with a substantial reduction in relapse events, compared to TC. Our study supports the current standard of practice, which is to use anthracycline-taxane and TC chemotherapy as a reasonable option in select cases.

Clinical and Genomic Risk for Late Breast Cancer Recurrence and Survival

BACKGROUND

The 21-gene recurrence score (RS) assay (Oncotype DX) is used to guide adjuvant chemotherapy use for patients with hormone receptor-positive, HER2 (human epidermal growth factor receptor 2)-negative, axillary node-negative breast cancer. Its role, however, in providing prognostic information for late distant recurrence when added to clinicopathologic prognostic factors is unknown.

METHODS

A patient-specific meta-analysis including 10,004 women enrolled in three trials was updated using extended follow-up data from TAILORx, integrating the RS with histologic grade, tumor size, and age at surgery for the RSClin tool. Cox models integrating clinicopathologic factors and the RS were compared by using likelihood ratio (LR) tests. External validation of prognosis for distant recurrence in years 0 to 10 and 5 to 10 was performed in an independent cohort of 1098 women in a real-world registry.

RESULTS

RSClin provided significantly more prognostic information than either the clinicopathologic factors (ΔLR chi-square, 86.2; P<0.001) or RS alone (ΔLR chi-square, 131.0; P<0.001). The model was prognostic in an independent cohort for distant recurrence by 10 years after diagnosis (standardized hazard ratio, 1.56; 95% confidence interval, 1.25 to 1.94), was associated with late distant recurrence risk between 5 and 10 years after diagnosis (standardized hazard ratio, 1.78; 95% confidence interval, 1.25 to 2.55), and approximated the observed 10-year distant recurrence risk (Lin concordance, 0.87) and 5- to 10-year distant recurrence risk (Lin concordance, 0.92).

CONCLUSIONS

The 21-gene RS is prognostic for distant recurrence and overall survival in early breast cancer. A model integrating the 21-gene RS and clinicopathologic factors improved estimates of distant recurrence risk compared with either used individually and stratified late distant recurrence risk. (Funded by the National Cancer Institute, National Institutes of Health [U10CA180820, U10CA180794, UG1CA189859, U10CA180868, and U10CA180822] and others.).

Does Sentinel Lymph Node Biopsy Influence Subsequent Management Decisions in Women With Breast Cancer ≥ 70 Years Old?

BACKGROUND

There have been ongoing attempts to de-escalate surgical intervention in older breast cancer patients in recent years. However, there remains ongoing hesitancy amongst surgeons to de-implement axillary staging in this cohort. The supporting argument for performing a sentinel lymph node biopsy (SLNB) is that it may guide subsequent management.

METHODS

A retrospective review was performed of 356 SLNBs, in 342 women ≥ 70 years of age with invasive breast cancer, between 2014 and 2022 in a single institution. Data were collected on patient and tumor characteristics and subsequent management for all patients and for patients with ER+/HER2-, early-stage disease.

RESULTS

Positive SLNB significantly increased likelihood of receiving adjuvant chemotherapy (CTh) in patients aged 70-75 in all clinical subtypes (OR 4.0, 95% CI, 1.6-10; P = .0035). Positive SLNB did not significantly increase likelihood of receiving adjuvant CTh in patients aged 75-80, however, an Oncotype Dx score of ≥ 26 did (OR 34.50, 95% CI, 3.00-455.2; P = .0103). Positive SLNB was significantly associated with receiving adjuvant radiotherapy (RTh) in all patients aged 70-75 (OR 4.5, 95% CI, 2.0-11; P = .0004) and 75-80 (OR 9.7, 95% CI, 2.7-46; P = .0015). In patients aged ≥ 80 years, positive SLNB did not have a significant influence on subsequent treatments.

CONCLUSION

In this study, SLNB did not significantly influence subsequent management decisions in patients over 80 and should rarely be performed in this cohort. However, SLNB still had a role in patients aged 70-80 and should be used selectively in this cohort.

Long-term prospective outcome data using EndoPredict as risk stratification and chemotherapy decision biomarker in hormone receptor-positive, HER2-negative early breast cancer

PURPOSE

To report the prospective long-term outcome data of patients whose chemotherapy decision was guided by the EndoPredict test.

METHODS

Patients with hormone receptor-positive HER2-negative early breast cancer with 0-3 positive lymph nodes were enrolled. The EndoPredict test was carried out on all tumor samples. Treatment compliance, local recurrence, distant metastases, and survival were evaluated. Associations of EPclin risk stratification with 5-year disease-free survival and distant metastasis-free survival were evaluated by time-to-event analysis.

RESULTS

368 consecutive patients were included in the analysis. Median follow-up was 8.2 years. EndoPredict allocated 238 (65%) in the low-risk and 130 (35%) patients in the high-risk group. Risk for disease recurrence or death in EPclin high-risk patients was twofold higher than in EPclin low-risk patients (hazard ratio [HR] 2.08; 95% CI 1.26-3.44; p = 0.004). EPclin low-risk patients had a 5-year disease-free survival of 95.3% (95% CI 92.6-98.0%). EPclin high-risk patients were at higher risk of developing distant metastases or death (HR 2.21; 95% CI 1.27-3.88; p = 0.005). EPclin high-risk patients who underwent chemotherapy had a 5-year DFS of 89.1% (95% CI 82.7-96.1%) in contrast to high-risk patients without chemotherapy (68.9%; 95% CI 56.2-84.5%; HR 0.46; 95% CI 0.23-0.95; p = 0.036). EPclin high-risk patients were at higher risk of experiencing distant metastases or death than EPclin low-risk patients regardless of menopausal status (premenopausal: HR 3.55; 95% CI 1.17-12.32; p = 0.025; postmenopausal: HR 1.92; 95% CI 0.99-3.7; p = 0.054).

CONCLUSION

EndoPredict can guide decisions on adjuvant chemotherapy in early luminal breast cancer. EndoPredict risk stratification is also applicable in premenopausal women.

Correlation Between Oncotype Dx Recurrence Score and PREDICT Estimates in Early Breast Cancer: A Single Institution Experience

PURPOSE

Oncotype Dx Recurrence Score (RS) is prognostic and predictive of chemotherapy benefit in women with node-negative and node-positive in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) early breast cancer. Nevertheless, its direct cost may be inhibitive. This study assesses the correlation between the RS and the free online PREDICT tools' estimations of adjuvant chemotherapy benefit.

PATIENTS AND METHODS

A retrospective review of the electronic medical records of 112 patients with tumors tested for the RS and the PREDICT tool was used to estimate survival benefits. The correlation between RS and PREDICT estimations was analyzed using Spearman rank and McNemar tests.

RESULTS

The median age of patients was 53 (95% CI, 50 to 55) years, with most patients having negative axillary lymph nodes (78%). While the absolute value for RS showed significant positive correlations with adjuvant chemotherapy's benefit as estimated by PREDICT, no significant correlations were found between the two methods in the percentage of chemotherapy gain. Notably, discordance rates between 48% and 67% between RS-based risk assignments and those based on PREDICT estimates were significant across the study population and subgroups. Only one disease recurrence and one breast cancer-related death were documented over a median follow-up of 23.5 (95% CI, 19.8 to 27.2) months.

CONCLUSION

Our findings highlight a significant discordance between RS and PREDICT tools in predicting the benefits of adjuvant chemotherapy in patients with HR+, HER2- early breast cancer. While both tools aim to personalize cancer treatment, their discordance varies, suggesting that PREDICT could not substitute RS to predict adjuvant chemotherapy benefits regardless of patient risk classification. Further studies are needed to explore these relationships and optimize precision medicine approaches in breast cancer management.

Selecting postoperative adjuvant systemic therapy for early-stage breast cancer: An updated assessment and systematic review of leading commercially available gene expression assays

Gene expression assays (GEAs) can guide treatment for early-stage breast cancer. Several large prospective randomized clinical trials, and numerous additional studies, now provide new information for selecting an appropriate GEA. This systematic review builds upon prior reviews, with a focus on five widely commercialized GEAs (Breast Cancer Index®, EndoPredict®, MammaPrint®, Oncotype DX®, and Prosigna®). The comprehensive dataset available provides a contemporary opportunity to assess each GEA's utility as a prognosticator and/or predictor of adjuvant therapy benefit.

Pathologic complete response after neoadjuvant systemic therapy for breast cancer in BRCA mutation carriers and noncarriers

BRCA1 and BRCA2 pathogenic variant carriers develop breast cancers with distinct pathological characteristics and mutational signatures that may result in differential response to chemotherapy. We compared rates of pathologic complete response (pCR) after NAC between BRCA1/2 variant carriers and noncarriers in a cohort of 1426 women (92 [6.5%] BRCA1 and 73 [5.1%] BRCA2) with clinical stage I-III breast cancer treated with NAC followed by surgery from 11/2013 to 01/2022 at Memorial Sloan Kettering Cancer Center. The majority received doxorubicin/cyclophosphamide/paclitaxel therapy (93%); BRCA1/2 carriers were more likely to receive carboplatin (p < 0.001). Overall, pCR was achieved in 42% of BRCA1 carriers, 21% of BRCA2 carriers, and 26% of noncarriers (p = 0.001). Among clinically node-positive (cN+) patients, nodal pCR was more frequent in BRCA1/2 carriers compared to noncarriers (53/96 [55%] vs. 371/856 [43%], p = 0.015). This difference was seen in HR+/HER2- (36% vs. 20% of noncarriers; p = 0.027) and TN subtypes (79% vs. 45% of noncarriers; p < 0.001). In a multivariable analysis of the overall cohort, BRCA1 status, and TN and HER2+ subtypes were independently associated with pCR. These data indicate that BRCA1 carriers may be more likely to achieve overall and nodal pCR in response to NAC compared with BRCA2 carriers and patients with sporadic disease. Further studies with a larger cohort of BRCA1/2 mutation carriers are needed, as a small sample size may have a restricted ability to detect a significant association between mutational status and pCR in sensitivity analyses stratified by subtype and adjusted for clinically relevant factors.

An Overview of Long-Acting GnRH Agonists in Premenopausal Breast Cancer Patients: Survivorship Challenges and Management

Managing breast cancer in premenopausal women poses unique challenges due to its considerable effect on both morbidity and mortality. Goserelin, a gonadotropin-releasing hormone agonist, has emerged among the various modalities as a preferred option for ovarian function suppression, owing to its efficacy in reducing ovarian estrogen production in premenopausal women with hormone receptor-positive breast cancer. Recent studies have affirmed the efficacy and safety of long-acting (LA) goserelin 10.8 mg every 12 weeks, offering comparable outcomes to monthly injections. This flexibility enables personalized treatment approaches, potentially enhancing patient satisfaction. Off-label utilization of goserelin LA surged during the coronavirus disease pandemic, prompting initiatives to broaden its use for breast cancer treatment. Switching to goserelin LA can streamline treatment, boost adherence, and optimize resource utilization. With the recent approval of goserelin 10.8 mg LA by Health Canada on 6 May 2024, for use in breast cancer, Canada is the latest to join over 60 countries worldwide to expand the accepted indications for goserelin LA and ensure its availability to potentially enhance healthcare delivery, patient care, and breast cancer outcomes. Goserelin LA offers premenopausal patients a means to more effectively manage the constraints imposed by breast cancer treatment and its impact on survivorship.

New Insight for Axillary De-Escalation in Breast Cancer Surgery: "SoFT Study" Retrospective Analysis

Background: The SOUND study demonstrated that an axillary de-escalation may be sufficient in locoregional and distant disease control in selected early breast cancer (EBC) patients. To establish any preoperative variables that may drive sentinel lymph node biopsy (SLNB) omission, a study named sentinel omission risk factor (SOFT) 1.23 was planned. Methods: A single-center retrospective study from a prospectively maintained database was designed, aiming at underlying preoperative prognostic factors involved in sentinel lymph node (SLN) metastasis (lymph node involvement (LN+) vs. negative lymph node (LN-) group). Secondary outcomes included surgical room occupancy analysis for SLNB in patients fulfilling the SOUND study inclusion criteria. The institutional ethical committee Area Territoriale Lazio 2 approved the study (n° 122/23). Results: Between 1 January 2022 and 30 June 2023, 160 patients were included in the study and 26 (%) were included in the LN+ group. Multifocality, higher cT stage, and larger tumor diameter were reported in the LN+ group (p = 0.020, p = 0.014, and 0.016, respectively). Tumor biology, including estrogen and progesterone receptors, and molecular subtypes showed association with the LN+ group (p < 0.001; p = 0.001; and p = 0.001, respectively). A total of 117 (73.6%) patients were eligible for the SOUND study and the potential operating room time saved was 2696.81 min. Conclusions: De-escalating strategies may rationalize healthcare activities. Multifactorial risk stratification may further refine the selection of patients who could benefit from SLNB omission.

Genomics in Clinical trials for Breast Cancer

Breast cancer (B.C.) still has increasing incidences and mortality rates globally. It is known that B.C. and other cancers have a very high rate of genetic heterogeneity and genomic mutations. Traditional oncology approaches have not been able to provide a lasting solution. Targeted therapeutics have been instrumental in handling the complexity and resistance associated with B.C. However, the progress of genomic technology has transformed our understanding of the genetic landscape of breast cancer, opening new avenues for improved anti-cancer therapeutics. Genomics is critical in developing tailored therapeutics and identifying patients most benefit from these treatments. The next generation of breast cancer clinical trials has incorporated next-generation sequencing technologies into the process, and we have seen benefits. These innovations have led to the approval of better-targeted therapies for patients with breast cancer. Genomics has a role to play in clinical trials, including genomic tests that have been approved, patient selection and prediction of therapeutic response. Multiple clinical trials in breast cancer have been done and are still ongoing, which have applied genomics technology. Precision medicine can be achieved in breast cancer therapy with increased efforts and advanced genomic studies in this domain. Genomics studies assist with patient outcomes improvement and oncology advancement by providing a deeper understanding of the biology behind breast cancer. This article will examine the present state of genomics in breast cancer clinical trials.

Development of a nomogram to predict recurrence scores obtained using Oncotype DX in Japanese patients with breast cancer

BACKGROUND

Chemotherapy is crucial for hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer, and its survival benefits may outweigh adverse events. Oncotype DX (ODX) assesses this balance; however, it is expensive. Using nomograms to identify cases requiring ODX may be economically beneficial. We aimed to identify clinicopathological variables that correlated with the recurrence score (RS) and develop a nomogram that predicted the RS.

METHODS

We included 457 patients with estrogen receptor-positive, HER2-negative breast cancer with metastases in fewer than four axillary lymph nodes who underwent surgery and ODX at our hospital between 2007 and 2023. We developed nomograms and internally validated them in 310 patients who underwent surgery between 2007 and 2021 and validated the model's performance in 147 patients who underwent surgery between 2022 and 2023.

RESULTS

Logistic regression analysis revealed that progesterone receptor (PgR) level, histological grade (HG), and Ki67 index independently predicted the RS. A nomogram was developed using these variables to predict the RS (area under the curve [AUC], 0.870; 95% confidence interval [CI], 0.82-0.92). The nomogram was applied to the model validation group (AUC, 0.877; 95% CI, 0.80-0.95). When the sensitivity of the nomogram was 90%, the model was able to identify 52.3% low-RS and 41.2% high-RS cases not requiring ODX.

CONCLUSIONS

This was the first nomogram model developed based on data from a cohort of Japanese women. It may help determine the indications for ODX and the use of nomogram to identify cases requiring ODX may be economically beneficial.

Gene Expression Assays to Tailor Adjuvant Endocrine Therapy for HR+/HER2- Breast Cancer

Adjuvant endocrine therapy (ET) represents the standard of care for almost all hormone receptor (HR)+/HER2- breast cancers, and different agents and durations are currently available. In this context, the tailoring and optimization of adjuvant endocrine treatment by reducing unnecessary toxic treatment while taking into account the biological heterogeneity of HR+/HER2- breast cancer represents a clinical priority. There is therefore a significant need for the integration of biological biomarkers in the choice of adjuvant ET beyond currently used clinicopathological characteristics. Several gene expression assays have been developed to identify patients with HR+/HER2- breast cancer who will not derive benefit from the addition of adjuvant chemotherapy. By enhancing risk stratification and predicting therapeutic response, genomic assays have also shown to be a promising tool for optimizing endocrine treatment decisions. In this study, we review evidence supporting the use of most common commercially available gene expression assays [Oncotype DX, MammaPrint, Breast Cancer Index (BCI), Prosigna, and EndoPredict] in tailoring adjuvant ET. Available data on the use of genomic tests to inform extended adjuvant treatment choice based on the risk of late relapse and on the estimated benefit of a prolonged ET are discussed. Moreover, preliminary evidence regarding the use of genomic assays to inform de-escalation of endocrine treatment, such as shorter durations or omission, for low-risk patients is reviewed. Overall, gene expression assays are emerging as potential tools to further personalize adjuvant treatment for patients with HR+/HER2- breast cancers.

Investigation of recurrence prediction ability of EndoPredict® using microarray data from fresh frozen tissues in ER-positive, HER2-negative breast cancer and indication expansion of EndoPredict® from microarray data from fresh-frozen to FFPE tissues

BACKGROUND

EndoPredict® (EP) is a multigene assay to predict distant recurrence risk in luminal breast cancer. EP measures the expression of 12 genes in primary tumor by qRT-PCR from formalin-fixed paraffin-embedded (FFPE) tissues and calculates EP risk score that indicates the risk of distant recurrence. We evaluated the performance of EP in predicting distant recurrence risk using microarray data from fresh frozen (FF) tissues. We also examined the applicability of EP to microarray data from FFPE tissues.

METHODS

We analyzed the publicly available data of 431 node-negative and 270 node-positive patients with luminal breast cancer who received endocrine therapy alone. We evaluated the prognostic value of EP using microarray data from FF tissues. Next, we created an algorithm to calculate EP risk score using microarray data from FFPE tissues. We examined the correlation coefficient of EP risk score and concordance rate of EP risk high/low using microarray data from FFPE/FF tissue pairs in a validation set of 39 patients.

RESULTS

In 431 node-negative patients, the distant recurrence-free survival (DRFS) rate was significantly worse in those with high EP risk scores (P = 3.68 × 10-6, log-rank). The 5-year DRFS was 95.2% in those with low EP risk score. In the validation set, the correlation coefficient of EP risk score was 0.93 and the concordance rate of EP risk high/low was 91.7%.

CONCLUSIONS

EP using microarray data from FF tissues was useful in predicting distant recurrence risk in luminal breast cancer, and EP might be utilized in microarray data from FFPE tissues.

BRCA1/2 mutation carriers vs the general breast cancer population (N = 799,986): 21-gene assay-based molecular characterization

PURPOSE

We compared 21-gene recurrence score (RS) distribution and expression of the single-gene/gene groups within this assay between BC patients with pathogenic variants (PV) in BRCA1/2 vs the general 21-gene-tested BC population.

METHODS

This retrospective study included consecutive 21-gene-tested female ER + HER2-negative BC patients with germline PVs in BRCA1/2. RS/gene expression data were compared to a previously described commercial use database (CDB, N = 799,986). Chi-square and 1-sample t test were used to compare RS distribution and single-gene/gene group scores between the study group and the CDB.

RESULTS

Study group patients (N = 81) were younger and their RS results were higher compared to the CDB (age: median [IQR], 56 [47-61.5] vs 60 [51-67] years; p < 0.001; proportion of patients with RS ≥ 26: 49.4% vs 16.4%, p < 0.001). Expression of 12/16 cancer genes in the assay and the ER, proliferation, and invasion gene group scores differed significantly between the study group and the CDB, all in a direction contributing to higher RS. The differences between the study group and the CDB were mostly retained, upon stratifying the patients by menopausal status.

CONCLUSION

BC patients with PVs in BRCA1/2 have higher RS results that stem from distinct gene expression profiles in the majority of genes in the 21-gene assay.