The Effect of Molecular Subtype and Residual Disease on Locoregional Recurrence in Breast Cancer Patients Treated with Neoadjuvant Chemotherapy and Postmastectomy Radiation.

Abstract

The relative contribution of biologic subtype to locoregional recurrence (LRR) in patients treated with neoadjuvant chemotherapy (NAC), mastectomy, and postmastectomy radiotherapy (PMRT) is not clearly defined. 233 patients with stages 2 and 3 breast cancer who received NAC, mastectomy, and PMRT between 2000 and 2009 were included: 53 % (n = 123) had HR+ (ER or PR+/HER2-), 23 % (n = 53) had HER2+ (HER2+/HR+ or HR-), and 24 % (n = 57) had triple-negative (TN) disease (HR-/HER2-). The 5-year LRR rates were estimated by Kaplan-Meier methods. Cox regression analysis was performed to evaluate covariates associated with LRR. The median follow-up period was 62 months. A pathologic complete response (pCR) was seen in 14 % of the patients. The 5-year LRR rate was 8 % for the entire cohort. The LRR rate was 0 % for the patients with a pCR versus 9 % for the patients without a pCR (p = 0.05). TN disease [Hazard ratio (HR) 4.4; p = 0.003] and pathologic node positivity (HR 9.8; p = 0.03) were associated with LRR. Patients with TN disease had a higher LRR rate than patients with HER2+ or HR+ disease (20 vs. 6 and 4 %; p = 0.005). Among patients without a pCR, TN subtype was associated with increased LRR risk (26 versus 7 % HER+ and 4 % HR+; p < 0.001). Patients with TN breast cancer had the highest LRR rate after NAC, mastectomy and PMRT. Whereas no LRR was observed among TN patients with a pCR, TN patients with residual disease had a significantly higher LRR risk. Patients with HR+ and HER2+ breast cancer had favorable LRR rates regardless of NAC response, likely due to receipt of adjuvant systemic targeted therapies.