Differential Pathological Response to Preoperative Chemotherapy across Breast Cancer Intrinsic Subtypes

BACKGROUND: Breast cancer is a heterogeneous disease with a diversity of clinical behaviors. The purpose of this study was to evaluate the utility of breast cancer intrinsic subtypes in the prediction of pathological complete response (pCR) in a cohort of breast cancer patients receiving preoperative chemotherapy. METHODS: Patients with stage II/III breast cancer received 4 cycles of XT (capecitabine and docetaxel) followed by 4 cycles of FEC (fluorouracil, epirubicin, and cyclophosphamide) as preoperative chemotherapy. Tumors were classified as luminal A, luminal B, luminal/HER2, HER2, basal-like, or non-basal-like triple negative by immunohistochemical analysis in core needle biopsy samples at baseline. RESULTS: The overall pCR rate was 11.9% (12/101). Multivariate analysis showed that intrinsic subtype was an independent factor to predict pCR. With luminal A patients as the reference group, luminal B (OR = 16.39; 95% CI 1.44-185.88; p = 0.024), HER2 (OR = 14.73; 95% CI 1.19-180.84; p = 0.035), and basal-like (OR = 13.27; 95% CI 1.27-138.79; p = 0.031) patients had a significantly higher likelihood of pCR. CONCLUSION: The present data indicate that intrinsic subtypes may be useful predictive biomarkers of pCR in breast cancer patients treated with preoperative chemotherapy.