The impact of adjuvant chemotherapy on overall survival in premenopausal (age≤50 years) hormone and node positive breast cancer patients with an Oncotype Dx score of 25 or less. A NCDB analysis

Purpose: The RxPONDER trial showed improved outcomes in premenopausal hormone positive breast cancer (BC) with 1-3 nodes and OncotypeDx (RS) score ≤ 25 with adjuvant chemotherapy (Chemo) use. Methods: The 2010-2018 National Cancer Database was used to include M0 BC patients aged ≤50 years with N1-N3 lymph nodes stages, any T stage, and RS ≤ 25. Kaplan-Meier (KM) and multivariate (MV) propensity score (PS) weighted Cox model was used to compare survival between patients without and with chemo. Results: 8628 women were included of which 3519 (40.8%) received chemo. KM curves showed that chemo use had better survival at 10 years (93 vs 91%) compared to hormonal therapy alone. Hazard Ratio (HR) comparison between the 2 groups favored chemo [0.602(0.482,0.751)]. Subgroup analysis for mortality benefits showed favorable results in Caucasian race [0.512(0.348,0.752)], both age groups of 18-40 years [0.429(0.217,0.847) and 40-50 years [0.585(0.394,0.869)], and RS 12-25 [0.549(0.379,0.795)]. Conclusions: Based on our analysis, chemo use was noted in 40.8% of young, lymph node+ BC patients with an RS score of 0-25. This group of patients had an overall survival advantage of around 40% with chemo use, further supporting the findings of the RxPONDER trial. This benefit is of particular significance in patients with a RS of 12-25. The survival advantage was present in all patients less than 50 years, regardless of the age subgroups.