Using Oncotype DX breast recurrence score® assay to define the role of neoadjuvant endocrine therapy in early-stage hormone receptor-positive breast cancer.

PURPOSE: The role of neoadjuvant endocrine therapy in the treatment of patients with early-stage, hormone receptor-positive (HR +) breast cancer is not well defined. Tools to better determine which patients may benefit from neoadjuvant endocrine therapy versus chemotherapy or upfront surgery remain an unmet need. METHODS: We assessed the rate of clinical and pathologic complete response (cCR, pCR) among a pooled cohort of patients with early-stage HR + breast cancer who had been randomized to neoadjuvant endocrine therapy or neoadjuvant chemotherapy in two earlier studies to understand better how outcomes varied by Oncotype DX Breast Recurrence Score® assay. RESULTS: We observed that patients with intermediate RS results had no statistically significant differences in pathologic outcomes at the time of surgery based on whether they received neoadjuvant endocrine therapy or neoadjuvant chemotherapy, suggesting that a subgroup of women with a RS 0-25 may omit chemotherapy without compromising outcomes. CONCLUSION: These data suggest that Recurrence Score® (RS) results may serve as a useful tool in treatment decision-making in the neoadjuvant setting.

Population-based estimate for the correlation of the Oncotype Dx Breast Recurrence Score® result and Ki-67 IHC MIB-1 pharmDx in HR+, HER2-, node-positive early breast cancer.

BACKGROUND: The United States Food and Drug Administration recently approved a Ki-67 immunohistochemistry (IHC) assay to identify patients with early breast cancer at high disease recurrence risk. The Oncotype Dx Breast Recurrence Score® assay has been validated in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) invasive breast cancer (IBC) to predict chemotherapy benefit and distant recurrence risk, regardless of nodal status. This study assessed the correlation between Recurrence Score® (RS) results and the Ki-67 IHC MIB-1 pharmDx assay. METHODS: HR+, HER2-, N1 IBC samples with RS results were examined by Ki-67 IHC; 311 specimens were collected, including 275 without regard to RS ("unselected RS") and 36 more with RS 26-100; 12 were lymph node negative upon pathology report review, and one had no Ki-67 score, leaving 262 unselected RS and 298 total samples. Spearman rank correlation was calculated using the unselected samples and a weighted rank correlation using all samples. A receiver operating characteristic (ROC) curve for predicting high RS (26-100) from Ki-67 was constructed. RESULTS: The Spearman rank correlation between Ki-67 and RS results was moderately positive (unselected RS samples: 0.396; 95% confidence interval [CI] 0.288-0.493; all samples: 0.394; 95% CI 0.294-0.486). While 71% of samples with RS 26-100 had Ki-67 ≥ 20%, 75% with RS 0-25 had Ki-67 < 20%. ROC area under the curve was 0.792 (95% CI 0.725-0.859). CONCLUSIONS: The moderately positive correlation is consistent with previous analyses suggesting the Oncotype Dx® assay and Ki-67 IHC MIB-1 assay should not be used interchangeably in clinical practice.

Expanding the Staging Criteria for T1-2N0 Hormone-Receptor Positive Breast Cancer Patients Enrolled in TAILORx.

BACKGROUND: The American Joint Committee on Cancer (AJCC) 8th edition pathologic prognostic staging (PPS) incorporates anatomic and biologic factors. The OncotypeDX Breast Recurrence Score (RS) was included based on the initial report of the TAILORx trial, with T1-2N0 hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer patients who had a RS < 11 staged as PPS 1A. This study examined whether the RS criteria for PPS 1A can be further expanded using patients enrolled in the TAILORx trial. METHODS: The TAILORx trial enrolled 10,273 HR+HER2- T1-2N0 patients. Those with incomplete HR-status/grade and T3 disease were excluded for analysis. The recurrence-free interval (RFI) was compared between the patients who did and those who did not fall into the current PPS 1A category using the Kaplan-Meier method. RESULTS: The study enrolled 9535 patients for analysis. The RS was < 11 in 16.1%, 11-17 in 35.9%, 18-25 in 32.4%, and > 25 in 15.6% of the patients. The majority (91.2%) of the patients (including all the T1N0 patients regardless of RS) were PPS 1A, and 8.8% were not-PPS 1A. The median follow-up time was 95 months. The PPS 1A patients had an 8-year RFI of 94.2%, which was similar to that of the patients with a RS of 11-17 who were not-PPS 1A (91.7%; p = 0.07) and better than that of the patients with a RS ≥ 18 who were not-PPS 1A (85.4% for a RS of 18-25, 76.0% for a RS > 25; both p < 0.01). Similar RFI trends were seen in patients who received endocrine therapy or chemotherapy followed by endocrine therapy. CONCLUSIONS: Patients with T1-2N0 HR+HER2- breast cancer and a RS < 18 have an RFI similar to that of patients staged as PPS 1A by the current AJCC staging system, regardless of treatment, suggesting that the criteria for PPS 1A can be expanded to include a RS < 18.

Response to neoadjuvant chemotherapy and the 21-gene Breast Recurrence Score test in young women with estrogen receptor-positive early breast cancer.

PURPOSE: The 21-gene Breast Recurrence Score test predicts benefit from adjuvant chemotherapy in estrogen receptor-positive, HER2-negative (ER+/HER2-) breast cancer (BC). We examined whether the 21-gene assay predicts response to neoadjuvant chemotherapy (NCT). METHODS: We identified patients with stage I-III ER+/HER2- BC treated with NCT from the Young Women's Breast Cancer Study, a prospective cohort of women diagnosed with BC at age ≤40 years. The 21-gene assay was performed on tumor specimens removed prior to NCT either as part of clinical care or retrospectively for research. Pathological complete response (pCR) was defined as ypT0/is ypN0. The relationship between Recurrence Score result and pCR was evaluated using logistic regression modeling. RESULTS: 76 women received NCT for ER+/HER2- BC and were eligible for this analysis. Median age at diagnosis was 37 years (range 24-40). Scores ranged between 5 and 77 with 50% >25 and 5% <11. Median Recurrence Score result was significantly higher among tumors achieving pCR vs. non-pCR response (61.5 vs. 23, pwilcoxon = 0.0005). pCR rate in patients with scores >25 was 21% (8/38) vs. 5% in patients with scores <25 (2/38) (p = 0.09), with both pCRs in the <25 group in patients with scores between 21 and 25. In multivariable analysis, only Recurrence Score result was significantly associated with pCR (OR: 1.07, 95%CI 1.01-1.12, p = 0.01). CONCLUSIONS: In young women with ER+/HER2- BC who received NCT, higher pretreatment Recurrence Score result was associated with an increased likelihood of pCR. Gene expression profile assays may have a role in decision making in young women in need of neoadjuvant therapy.

Discordance in Oncotype DX Breast Recurrence Score® Results for Bilateral Breast Cancer.

BACKGROUND: The Oncotype DX Breast Recurrence Score® assay is a clinically useful tool to determine the benefit of chemotherapy in the treatment of early-stage, hormone-receptor-positive breast cancer. Bilateral breast cancer (BBC) is found in ~ 5% of patients with breast cancer, and data regarding discordance of Oncotype DX results between BBC defined by current TAILORx subgroups are limited. Our goals are to study the rate of Oncotype DX discordance between BBC and investigate whether such differences can affect chemotherapy treatment discussions. METHODS: Patients with BBC were identified in US samples submitted to Genomic Health for 21-gene testing between January 2019 and July 2020. The risk categories were defined as 0-25 and 26-100 as well as 0-17, 18-30, and 31-100 for all patients. Subgroup analysis was also performed for node-negative women age ≤ 50 years with Recurrence Score results of 0-15, 16-20, 21-25, and 26-100. RESULTS: 944 BBC patients with known nodal status (702 node negative, 242 node positive) were identified and included. Among node-negative patients aged > 50 years, the rate of discordance in Recurrence Score by group (0-25 and 26-100) was 4.2% (n = 598). For node-negative patients aged ≤ 50 years, the risk group was discordant in < 3% when considering the risk grouping of 0-25 and 26-100. However, upon subgroup analysis based on TAILORx analysis, the rate of discordance was 48.1% in these younger patients (n = 104). CONCLUSIONS: This study shows that a clinically relevant rate of discordance in Oncotype DX results in patients with BBC may impact medical decision-making regarding chemotherapy.

Factors associated with MRI detection of occult lesions in newly diagnosed breast cancers.

BACKGROUND: The use of preoperative magnetic resonance imaging (MRI) for newly diagnosed breast cancer remains controversial. We examined factors associated with detection of occult multicentric, multifocal, and contralateral malignant lesions only seen by MRI. METHODS: We performed a retrospective analysis of consecutive patients undergoing preoperative MRI for breast cancer. Clinicopathologic data were assessed regarding the findings of multifocality, multicentricity, and the presence of contralateral lesions. We analyzed the association of factors with these findings on MRI. RESULTS: Of 857 patients undergoing MRI, 770 patients met inclusion criteria. Mean age was 54.7 years. Biopsy-proven detection rates by MRI for multifocal, multicentric, and contralateral cancers were 6.2% (48 of 770), 1.9% (15 of 770) and 3.1% (24 of 770), respectively. African American race and heterogeneously or extremely dense mammographic density were associated with multifocal cancers on MRI. Larger lesion size and mammographic density were associated with multicentric cancers. Invasive lobular carcinoma (ILC) and progesterone receptor (PR)-positivity were associated with contralateral cancers. CONCLUSIONS: African American race, heterogeneously or extremely dense mammographic density, ILC, and PR-positivity were associated with additional biopsy-proven cancers based on MRI. These factors should be considered when assessing the clinical utility of preoperative breast MRI.

Correction to: Lymph Node Status in Breast Cancer Does Not Predict Tumor Biology.

In the "Results" section third paragraph, second sentence, there is an error. The corrected sentence is as follows.

Lymph Node Status in Breast Cancer Does Not Predict Tumor Biology.

BACKGROUND/OBJECTIVE: The 21-gene Oncotype DX® Breast Recurrence Score® (RS) assay has been prospectively validated as prognostic and predictive in node-negative, estrogen receptor-positive (ER+)/HER2- breast cancer patients. Less is known about its prognostic role in node-positive breast cancer. We compared RS results among patients with lymph node-negative (N0), micrometastatic (N1mi), and macrometastatic (N+) breast cancer to determine if nodal metastases are associated with more aggressive biology, as determined by RS. METHODS: Overall, 610,350 tumor specimens examined by the Genomic Health laboratory from February 2004 to August 2017 were studied. Histology was classified centrally, while lymph node status was determined locally. RS distribution (low: < 18; intermediate: 18-30; high: ≥ 31) was compared by nodal status. RESULTS: Eighty percent (n = 486,013) of patients were N0, 4% (n = 24,325) were N1mi, 9% (n = 56,100) were N+, and 7% (n = 43,912) had unknown nodal status. Mean RS result was 18, 16.7, 17.3 and 18.9 in the N0, N1mi, N+, and unknown groups, respectively. An RS ≥ 31 was seen in 10% of N0 patients, 7% of N1mi patients, and 8.0% of N+ patients. The likelihood of an RS ≥ 31 in N1mi and N+ patients varied with tumor histology, with only 2% of patients with classic infiltrating lobular cancer having an RS ≥ 31, versus 7-9% of those with ductal carcinoma. CONCLUSIONS: RS distribution among N0, N1mi, and N+ patients is similar, suggesting a spectrum of biology and potential chemotherapy benefit exists among node-negative and node-positive ER+/HER2- breast cancer patients. If RxPONDER does not show a chemotherapy benefit in N+ patients with a low RS result, our findings indicate that substantial numbers of patients could be spared the burden of chemotherapy.

Value of routine staging imaging studies for patients with stage III breast cancer.

BACKGROUND AND OBJECTIVES: Routine staging imaging studies (RSIS) are optional in stage III breast cancer (BC). The impact of RSIS on treatment decisions and patient outcomes has not been extensively studied. The goal of this study was to determine whether RSIS in stage III BC affected treatment or patient outcomes. METHODS: Stage III BC patients from 2000 to 2010 were retrospectively identified. RSIS results and treatment plan in response to RSIS results were recorded. Univariate and multivariate Cox proportional hazards regression models with time-dependent covariates were used to assess associations between RSIS use and recurrence-free survival (RFS). RESULTS: Of 420 patients, 362 (86.2%) received RSIS. RSIS were negative in 264 (72.9%), indeterminate in 77 (18.3%), and positive in 21 patients (5.0%) for metastatic disease. Treatment was altered in 21 (5.8%) patients based on RSIS results (20 with metastatic disease, 1 with indeterminate disease). There was no difference in RFS with RSIS use on multivariate analysis (hazard ratio 1.3; 95% confidence interval 0.73-2.5, P = 0.32). CONCLUSIONS: Most stage III BC patients underwent RSIS, but RSIS results infrequently affected treatment decisions. There was no significant difference in RFS with RSIS use. RSIS to identify metastatic disease for stage III BC has limited value. J. Surg. Oncol. 2016;114:917-921. © 2016 Wiley Periodicals, Inc.

Lymph node status in inflammatory breast cancer.

Positive lymph node status in breast cancer is known to be an adverse prognostic factor, but the effect of lymph node (LN) status in inflammatory breast cancer (IBC) has not been evaluated. This study was designed to investigate the association between lymph node status and overall survival (OS) in individuals with IBC. Using the Surveillance, Epidemiology, and End Results (SEER) 18 registry, we collected data on 761 patients diagnosed with non-metastatic IBC from 2004 to 2008. Survival analysis was performed using the Kaplan-Meier method. Cox proportional hazard regression was performed to evaluate univariate and multivariate associations between estrogen and progesterone receptor (ER/PR) status, treatment, and OS. Positive nodal status was associated with a significant decrease in OS (p < 0.001). Five-year survival for LN-positive and LN-negative patients was 49 and 66 %, respectively. In node-positive patients, ER or PR positivity was associated with improved OS, (p = 0.025, p = 0.007). In node-positive patients, the combination of surgery and radiation therapy improved OS when compared with surgery alone (p = 0.002). Nearly 80 % of the patients in this study had nodal metastasis. Positive nodal status was found to be an adverse prognostic factor. ER/PR positivity and treatment with surgery and radiation in node-positive patients was found to improve outcomes. Further studies are required to characterize the biology of IBC and guide the optimal treatment of this disease.

Nurse-Led Multidisciplinary Heart Failure Group Clinic Appointments: Methods, Materials, and Outcomes Used in the Clinical Trial.

BACKGROUND: The Self-management and Care of Heart Failure through Group Clinics Trial evaluated the effects of multidisciplinary group clinic appointments on self-care skills and rehospitalizations in high-risk heart failure (HF) patients. OBJECTIVE: The purpose of this article is to (1) describe key Self-management and Care of Heart Failure through Group Clinics Trial group clinic interactive learning strategies, (2) describe resources and materials used in the group clinic appointment, and (3) present results supporting this patient-centered group intervention. METHODS: This clinical trial included 198 HF patients (randomized to either group clinical appointments or to standard care). Data were collected from 72 group clinic appointments via patients' (1) group clinic session evaluations, (2) HF self-care behaviors skills, (3) HF-related discouragement and quality of life scores, and (4) HF-related reshopitalizations during the 12-month follow-up. Also, the costs of delivery of the group clinical appointments were tabulated. RESULTS: Overall, patients rated group appointments as 4.8 of 5 on the "helpfulness" in managing HF score. The statistical model showed a 33% decrease in the rate of rehospitalizations (incidence rate ratio, 0.67) associated with the intervention over the 12-month follow-up period when compared with control patients (χ(2)1=3.9, P=.04). The total cost for implementing 5 group appointments was $243.58 per patient. CONCLUSION: The intervention was associated with improvements in HF self-care knowledge and home care behavior skills and managing their for HF care. In turn, better self-care was associated with reductions in HF-related hospitalizations.

Cost-Effectiveness Analysis of the Oncotype DX Breast Recurrence Score® Test from a US Societal Perspective.

Background and Objectives: The 21-gene assay (the Oncotype DX Breast Recurrence Score® test) estimates the 10-year risk of distant recurrence in hormone receptor positive (HR+) and human epidermal growth factor receptor 2 negative (HER2-) early-stage breast cancer to inform adjuvant chemotherapy decisions. The cost-effectiveness of the 21-gene assay compared against standard clinical-pathological risk tools alone for HR+/HER2- early-stage breast cancer was assessed using an economic model informed by evidence from randomized controlled trials. Materials and Methods: A cost-effectiveness model consisted of a decision-tree to stratify patients according to their Recurrence Score (RS) results and the use of adjuvant chemotherapy, followed by a Markov component to estimate the long-term costs and outcomes of the chosen treatment. Distributions of patients and distant recurrence probabilities were derived from the TAILORx (N0) and RxPONDER (N1) trials. The model was evaluated from a healthcare payer and societal perspective. Endocrine therapy and chemotherapy use were informed using clinical expert opinion to reflect US clinical practice and were combined with Medicare drug costs (2021) to estimate the cost of treatment. Societal costs included lost productivity and patient out-of-pocket costs obtained from literature. Results: The Oncotype DX test generated more quality-adjusted life-years (QALYs) (N0: 0.25; N1: 0.08) at a lower cost (N0: -$13,395; N1: -$2526) compared to clinical-pathological risk alone from a societal cost perspective. The overall conclusions from the model did not change when considering a payer perspective. The main cost drivers were avoidance of distant recurrence for N0 (-$12,578), and the cost of adjuvant chemotherapy for N1 (-$2133). Lost productivity had a major impact in the societal perspective analysis (N0: -$4607; N1: -$1586). Conclusion: Adjuvant chemotherapy decisions based on the RS result led to more life year gains and lower healthcare costs (dominant) compared to using clinical-pathological risk factors alone among patients with HR+/HER2- N0 and N1 early-stage breast cancer.

The budget impact of utilizing the Oncotype DX Breast Recurrence Score test from a US healthcare payer perspective.

BACKGROUND AND OBJECTIVES: The Oncotype DX Breast Recurrence Score test is used to estimate distant recurrence risk of hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) early-stage breast cancer and inform decisions on the use of adjuvant chemotherapy. A model-based budget impact analysis compared the Oncotype DX test in combination with clinical-pathological risk against using clinical-pathological risk alone for HR+/HER2- node-negative (N0) and node-positive (N1; 1-3 axillary lymph nodes) early-stage breast cancer patients. MATERIALS AND METHODS: Test and medical costs associated with treatment of breast cancer were assessed through a US healthcare payer perspective. Distributions of patients by Recurrence Score result and distant recurrence probabilities with chemo-endocrine and endocrine therapy were derived from the TAILORx (N0) and RxPONDER (N1) trials. Changes in budget impact were evaluated over a 5-year horizon for a 1,000,000-member hypothetical health plan. RESULTS: With the Oncotype DX test, there was an incremental budget impact of $261,067 (per member per month (PMPM): $0.004), in the N0 population, and $56,143 (PMPM: $0.001) in the N1 population over the 5-year period. The largest budget impact reduction in the N0 population was attributed to reduced breast cancer recurrence costs (incremental: -$633,457, PMPM: -$0.011), while chemotherapy sparing reduced costs in the N1 population (incremental: -$94,884, PMPM: -$0.002). CONCLUSION: The clinical benefit of using the Oncotype DX test to inform adjuvant chemotherapy decisions has been shown in multiple randomized controlled trials. This analysis demonstrated that while using the Oncotype DX test to inform adjuvant chemotherapy decisions may slightly increase US healthcare costs over an initial 5-year time horizon (driven by a cost increase in the first year with cost savings reflected in remaining 4 years), there is significant scope for cost savings when assessing beyond this period due to avoided downstream costs of distant recurrence and long-term chemotherapy adverse events. PMPM costs also remain low across all populations examined, demonstrating a close-to-neutral budget impact.

Ductal carcinoma in situ (DCIS) of the breast: perspectives on biology and controversies in current management.

The incidence of ductal carcinoma in situ (DCIS) has increased because of increasing use of sensitive imaging modalities. MRI is commonly used for the detection of breast cancer but has not yet been validated in randomized trials. There have not been randomized trials addressing optimal margins of excision or axillary sampling. Whole breast radiation after lumpectomy decreases the risk of recurrence but may be omitted in selected patients. Adjuvant Tamoxifen reduces the risk of recurrence but has no impact on overall survival rates.

Expanding Criteria for Prognostic Stage IA in Hormone Receptor-Positive Breast Cancer.

BACKGROUND: The prognostic significance of patients with low-risk recurrence score (RS) results in the context of the American Joint Committee on Cancer (AJCC) eighth edition pathologic prognostic staging has not been investigated. We evaluated if expanded RS criteria can be considered for downstaging in AJCC pathologic prognostic staging. METHODS: Using Surveillance, Epidemiology, and End Results data, we identified patients with T1-3N0-3M0 hormone receptor-positive, HER2-negative breast cancer treated from 2010 to 2015 with follow-up data through 2016. We evaluated TNM categories, grade, and RS result. The primary outcome measured was 5-year disease-specific survival (DSS) of patients with low-risk RS results not already pathologic prognostic stage IA, determined by T and N categories per AJCC eighth edition. All statistical tests were 2-sided. RESULTS: Of 154 050 patients with median follow-up of 49 months (range = 0-83), RS results were obtained in 60 886 (39.5%): RS was less than 11 in 13 570 (22.3%); 11-17 in 22 719 (37.3%); 18-25 in 16 521 (27.1%); and 26 or higher in 8076 (13.3%). Five-year DSS for pathologic prognostic stage IA patients (n = 114 910, 74.6%) was 98.8%. Among N0-1 patients with a RS less than 18 not staged as pathologic prognostic stage IA by current criteria, 5-year DSS was excellent and not statistically significantly different than for pathologic prognostic stage IA patients (97.2%-99.7%; P > .05). For those with a RS of 18-25, there was a small decrease in DSS for T2N0 (2.3%) and modest decrease for T1-2N1 (4.2%-6.4%) compared with pathologic prognostic stage IA patients (P < .001). CONCLUSION: Patients with a RS less than 18 have excellent 5-year DSS regardless of T category for N0-1 disease suggesting further modification of the AJCC staging system using this cutoff.

Neoadjuvant therapy for breast cancer.

The past few decades have seen an increase in both the role and the complexity of neoadjuvant therapy for breast cancer. Neoadjuvant therapy was initially described as systemic chemotherapy for inflammatory or locally advanced breast cancer but now entails a combination of chemotherapy, endocrine therapy, and targeted therapy. Neoadjuvant systemic therapy is employed for inoperable inflammatory and locally advanced breast cancer, and also for patients with operable breast cancers who desire breast-conserving therapy (BCT) but are not candidates based on the initial size of the tumor in relation to the size of the breast. Neoadjuvant therapy in this subset of patients may impact the surgical options. This review will summarize the benefits of neoadjuvant systemic therapy and implications for BCT, the timing of sentinel node biopsy, and the utility of magnetic resonance imaging (MRI) to predict response to therapy.

Young-Onset Colon Cancer and Recurrence Risk by Gene Expression.

The incidence and mortality from colorectal cancer in younger adults (younger than 55 years) is increasing. We reviewed the complete database of a gene-expression test, Oncotype DX Colon Recurrence Score test, to determine age-related differences in recurrence score (RS) and single-gene results (7 cancer-related of the 12-gene assay). We included 20 478 stage II and III A and B colon cancer patients submitted to Genomic Health. RS results were grouped by low-, intermediate-, and high-risk groups. Single-gene scores were described using median and interquartile range. Of all patients 72.5% and 72.6% of those younger than 40 years had low-risk RS. Comparing older with younger patients, RS or single-gene expression did not differ by age group or stage. Young-onset colon cancer does not differ by expression of the RS component genes. Most patients with stage II and III colon cancer have low-risk disease as measured by the 12-gene assay, regardless of age.

Prognostic Impact of the 21-Gene Recurrence Score Assay Among Young Women With Node-Negative and Node-Positive ER-Positive/HER2-Negative Breast Cancer.

PURPOSE: The 21-gene recurrence score (RS) assay is prognostic among women with early-stage estrogen receptor-positive (ER+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer and is used to inform recommendations for chemotherapy. Women ≤ 40 years of age represent a minority of patients studied using gene expression profiles. METHODS: The Young Women's Breast Cancer Study is a prospective cohort of women diagnosed with breast cancer at age ≤ 40 years and enrolled patients between 2006 and 2016 (N = 1,302). We identified patients with stage I-III ER+/HER2- breast cancer. The RS assay was performed on banked specimens for patients who had not been tested clinically. Distant recurrence-free survival (DRFS) was assessed by TAILORx and traditional RS risk groups among patients with axillary node-negative (N0) and limited node-positive (N1) breast cancer. RESULTS: Among eligible women (N = 577), 189 (33%) had undergone RS testing, and 320 (56%) had banked specimens sufficient for testing. Median follow-up was 6.0 years. Median age at diagnosis was 37.2 years; 300 of 509 patients (59%) had N0 breast cancer, of whom 195 (65%) had an RS of 11-25 and fewer than half (86 of 195; 44%) received chemotherapy. Six-year DRFS rates were 94.4% and 92.3% (RS < 11), 96.9% and 85.2% (RS 11-25), and 85.1% and 71.3% (RS ≥ 26) among women with N0 and N1 disease, respectively. CONCLUSION: The RS assay is prognostic among young women with node-negative and limited node-positive breast cancer, representing a valuable tool for risk stratification. Disease outcomes with a median follow-up of 6 years among young women with N0 disease and an RS of 0-25, a minority of whom received chemotherapy, and node-positive disease with an RS < 11 were very good, whereas those with N0 disease and an RS ≥ 26 or N1 disease with an RS ≥ 11 experienced substantial risk of early distant recurrence.