Background: The aim of this study is to identify whether the breast cancer subtypes are predictors of pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) and survival in patients with T4 noninflammatory breast cancer.
Methods: The records of 181 patients treated with anthracycline +/- taxane based NAC followed by mastectomy and radiation therapy +/- hormonotherapy were evaluated. The role of intrinsic subtypes of the tumor including luminal A, luminal B, HER2, and triple-negative on pCR and survival were analyzed.
Results: The median follow-up was 44 months (range: 16-82 months). All patients received a median four cycles of NAC. Twenty-three patients (12.7%) were found to have pCR. In the univariate analysis, the intrinsic subtypes of the tumor had significant effect on pCR (p < 0.01). Also, intrinsic subtypes were significant predictors of pCR to NAC in the multivariate analysis (p < 0.01; hazard ratio, 2.4; 95% confidence interval, 1.1-6.8). While patients with triple-negative tumors had the highest rate of pCR (29%), this rate was the lowest in patients with HER2 tumors (4.2%). Five-year DFS was also significantly lower in patients with triple-negative (24%) and HER2 (21%) tumors compared to luminal A (61%) subtype (p < 0.0001). Likewise, 5-year OS was poorer in patients with triple-negative tumors (30%) and HER2 tumors (%31) compared to both luminal A (70%) and luminal B (68%) subtypes (p < 0.0001).
Conclusions: It can be concluded that breast cancer subtyping defines the extent of response to NAC and has a significant effect on survival in patients with T4 noninflammatory breast cancer.