Adjuvant chemotherapy is associated with an overall survival benefit regardless of age in patients with ER+/HER2-breast cancer with 1-3 positive nodes and Oncotype DX recurrence score 20 to 25: A National Cancer Database analysis.

person Lifen Cao University Hospitals at Cleveland Medical Center, Cleveland, OH info_outline Lifen Cao, Christopher W. Towe, Xun Luo, Nickolas Stabellini, Amanda L. Amin, Alberto J. Montero

Authors person Lifen Cao University Hospitals at Cleveland Medical Center, Cleveland, OH info_outline Lifen Cao, Christopher W. Towe, Xun Luo, Nickolas Stabellini, Amanda L. Amin, Alberto J. Montero Organizations University Hospitals at Cleveland Medical Center, Cleveland, OH, Case Western Reserve University, Cleveland, OH, NSABP Foundation, Cleveland Clinic, Cleveland, OH Abstract Disclosures Research Funding Other Background: Based on the results of the RxPonder trial, post-menopausal women over age 50 with estrogen receptor (ER)+ breast cancer, 1-3+ nodes, and a 21-gene Oncotype DX recurrence score (RS) score of <25, did not benefit from receiving adjuvant chemotherapy. By contrast, adjuvant chemotherapy was beneficial in premenopausal women. We aimed to replicate the RxPonder trial using a larger sample sizes with real world data to determine whether a threshold with RS exists where adjuvant chemoendocrine therapy (CET) is beneficial regardless of age. Methods: The National Cancer Database (NCDB) was queried for women with ER+, human epidermal growth factor receptor 2 (HER2) negative breast cancer, 1-3 positive axillary nodes, and RS <25 who received endocrine therapy (ET) only or CET. Interaction was explored between CET and age as a surrogate for menopausal status in the Cox regression models. Results: The final analytic cohort included 28,427 eligible women: 7,487 (26.3%) received adjuvant CET and 20,940 (73.7%) ET. In the entire cohort, RS had a normal distribution, with a median score of 14. After correcting for demographic and clinical variables, a threshold effect was observed with RS >20 being associated with a significantly inferior overall survival (OS) (P value range: < 0.001-0.019). In women with RS of 20-25, CET was associated with a significant improvement in OS compared to ET alone, regardless of age (age < = 50: HR = 0.334, P = 0.002; age > 50: HR = 0.521, P = 0.019). Conclusions: Among women with ER+/HER2- breast cancer with 1–3 positive nodes, and RS of 20-25, in contrast to the RxPonder trial we observed that CET was associated with an OS benefit in women regardless of age.