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.

Abstract

540 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.