Clinical outcomes according to molecular subtypes in stage II-III breast cancer patients treated with neoadjuvant chemotherapy followed by surgery and radiotherapy

Aim We evaluated the tumor response and clinical outcomes according to molecular subtypes in stage II–III breast cancer patients who received neo-adjuvant chemotherapy (NAC) followed by surgery and radiotherapy. Methods We retrospectively analyzed 329 patients with clinical stage II–III breast cancer who received NAC followed by surgery and radiotherapy. Luminal A and B, HER2-enriched and triple-negative subgroups were identified. Results The overall pathologic complete response (pCR) rate after NAC was 20.1% and the HER2-enriched subgroup had the highest pCR rate (43.6%), whereas luminal A showed the lowest rate of pCR (4.6%). The median follow-up duration was 55 months (range, 5–98 months). The 5-year overall survival (OS) and disease-free survival (DFS) rates were 88.9% and 72.9%, respectively. In subgroup analysis, according to the pathologic response (pCR vs non-pCR), the triple-negative subtype exhibited a significant difference in 5-year OS rate (100.0% vs 71.6%, P = 0.005) and 5-year DFS rate (93.1% vs 55.1%, P < 0.001). A distinct survival difference according to molecular subtype was found, particularly in the non-pCR group (5-year OS and DFS, P < 0.001, respectively). Conclusions The non-pCR group showed significantly decreased 5-year OS and DFS rates compared to the pCR group, especially in triple negative and HER2-enriched breast cancer patients. A significant difference in survival rates and molecular subtypes was found in patients who failed to attain pCR.