Use of neoadjuvant versus adjuvant chemotherapy for hormone receptor-positive breast cancer: a National Cancer Database (NCDB) study.

INTRODUCTION

Neoadjuvant chemotherapy (NAC) is a well-established therapeutic option for patients with locally advanced disease often allowing downstaging and facilitation of breast conserving therapy. With evolution of better targeted treatment regimens and awareness of improved outcomes for significant responders, use of NAC has expanded particularly for triple negative and HER2-positive (HER2+) breast cancer. In this study, we explore utility of neoadjuvant chemotherapy for hormone receptor-positive HER2-negative (HR+ HER2-) patients.

METHODS

Patients with HR+ HER2- breast cancer treated with chemotherapy before or after surgery were identified from 2010 to 2015 in the NCDB. Multivariable regression models adjusted for covariates were used to determine associations within these groups.

RESULTS

Among 134,574 patients (clinical stage 2A, 64%; 2B, 21%; 3, 15%), 105,324 (78%) had adjuvant chemotherapy (AC) and 29,250 (22%) received NAC. Use of NAC increased over time (2010-2015; 13.2-19.4% and PR = 1.34 for 2015; p < 0.0001). Patients were more likely to receive NAC with cT3, cT4, and cN+ disease. Patients less likely to receive NAC were age ≥ 50, lobular carcinoma, increased Charlson-Deyo score, and government insurance. Complete response (pCR) was noted in 8.3% of NAC patients. Axillary downstaging occurred in 21% of patients, and predictors included age < 50 years, black race, poorly differentiated grade, invasive ductal histology, and either ER or PR negativity.

CONCLUSIONS

NAC use among HR+ HER2- breast cancer patients has expanded over time and offers downstaging of disease for some patients, with pCR seen in only a small subset, but downstaging of the axilla in 21%. Further analysis is warranted to determine the subgroup of patients with HR+ HER2- disease who benefit from this approach.