Efficacy of neoadjuvant chemotherapy (NAC) in male breast cancer (MaBC) compared with female breast cancer (FBC): A National Cancer Database (NCDB) study.

Abstract

587 Background: NAC is frequently used in the treatment of FBC. The efficacy of NAC in MaBC is unclear. Few studies have compared outcomes for MaBC and FBC after similar treatment. The aim of this study was to compare proportions of pathologic complete response (pCR) between MaBC and FBC according to tumor subtype (TS). Secondary aims were clinical response and overall survival (OS). Methods: We evaluated men and women with breast cancer treated with NAC between 2010 and 2016 with known hormone receptor (HR) status and human epidermal growth factor receptor 2 (HER2) status at NCDB centers. The proportion with pCR (ypT0/Tis ypN0) was compared for MaBC and FBC for each TS by Fisher’s exact test. Logistic regression evaluated odds of pCR. OS was estimated by Kaplan-Meier and compared by log-rank test. Results: Of 7,721 MaBC and 859,096 FBC patients, 385 MaBC (5%) and 68,065 FBC (7.9%) underwent NAC and were included in this study. Median age for MaBC was 58 years (y) (range 23-88) and for FBC was 53 y (range 18-90). Within each TS, there were no significant differences in the distribution of tumor grade between MaBC and FBC. Clinical stage in MaBC and FBC were: Stage I: 8% v 11%, Stage II: 54% v 59%, Stage III: 38% v 30%; respectively. Median time from initiation of NAC to surgery was 143 days in MaBC and 148 days in FBC. Compared with FBC, MaBC had a lower proportion of complete clinical response (18% v 31%) and a higher proportion of no clinical response (14% v 7%); p < 0.001. Proportions and odds of pCR were numerically lower in MaBC compared with FBC for each TS and statistically significant for HR+/HER2- and HR+/HER2+ (table). pCR was associated with OS in both MaBC and FBC. Specifically, in MaBC who achieved pCR v not, 5 y OS was 90% v 64.7%; p = 0.02. In FBC who achieved pCR v not, 5 y OS was 91.9% v 75.3%; p < 0.01. Among pts receiving NAC, MaBC had worse OS at 5 y than FBC (67.1% v 79.0%; p = 0.02). Conclusions: Men receiving NAC achieved lower proportions of pCR than women and had significantly worse OS. However, pCR is prognostic in both MaBC and FBC. Limitations include small sample sizes for HR-/HER2+ and triple-negative TS and lack of detailed regimen information. Nevertheless, our results suggest that, compared with FBC, MaBC may be intrinsically more resistant to NAC. [Table: see text]