Tumor Biology and Response to Chemotherapy Impact Breast Cancer-specific Survival in Node-positive Breast Cancer Patients Treated with Neoadjuvant Chemotherapy

Background: Women with node-positive breast cancer are at high risk for recurrence. We evaluate the impact of approximated tumor subtype and response to chemotherapy on long-term outcomes in a node-positive cohort receiving neoadjuvant chemotherapy. Methods: ACOSOG Z1071 enrolled cT0-4N1-2 breast cancer patients treated with neoadjuvant chemotherapy from 2009 to 2011. Factors impacting breast cancer-specific survival (BCSS) and overall survival (OS) were analyzed. Results: Median follow-up of 701 eligible patients was 4.1 years (0.4-6.5). Ninety patients (12.8%) died from breast cancer. Approximated subtype and chemotherapy response were significantly associated with BCSS and OS (P < 0.0001). BCSS and OS were highest in patients who achieved pathologic complete response (pCR) (P < 0.0001 and P < 0.0001, respectively). Five-year BCSS was highest in human epidermal growth factor receptor 2 (HER2)-positive disease [95.8%; 95% confidence interval (CI): 87.7-98.6], followed by hormone receptor-positive/HER2-negative (80.4%; 95% CI: 73.2-85.9) and lowest in triple-negative (TNBC) (74.8%; 95% CI: 66.6-81.2; P < 0.0001). Similar patterns were seen in OS. In TNBC (n = 174), 5-year BCSS was higher in patients with pCR versus residual disease (89.8%; 95% CI: 78.8-95.3 vs 65.8%; 95% CI: 54.5-74.9; P = 0.0013). In hormone receptor-positive/HER2-negative (n = 318) disease, BCSS was 100% in patients with pCR and 78.3% (95% CI: 70.4-84.3) in those with residual disease (P = 0.018). In HER2-positive disease (n = 204) there was no difference between pCR and residual disease (96.0%; 95% CI: 83.6-99.1 vs 95.8%; 95% CI: 81.4-99.1; P = 0.77). Conclusions: In node-positive breast cancer patients treated with neoadjuvant chemotherapy, BCSS and OS were associated with approximated subtype and chemotherapy response and were lowest in TNBC patients with residual disease. Five-year BCSS was > 95% in HER2-positive disease independent of chemotherapy response.