Molecular subtypes as a predictor of response to neoadjuvant chemotherapy in breast cancer patients

PURPOSE: The objective of this study was to assess response to neoadjuvant chemotherapy in molecular subtypes of breast cancer. METHODS: This study included 60 patients with locally advanced and metastatic breast cancer. The authors excluded patients who already underwent mastectomy or were given any chemotherapy/radiotherapy. They analyzed the clinical and immunohistochemical characteristics using core biopsy specimens to determine their correlations with response to chemotherapy. RESULTS: A clinical complete response was observed in 19 patients (31.7%), a clinical partial response in 30 patients (50%), clinical stable disease in 8 patients (13.3%), and progressive disease in 3 patients (5%). A pathologic complete response (pCR) was observed in 7 (21.87%) of 32 patients who underwent surgery. High Ki-67 was associated with human epidermal growth factor receptor 2 (HER2)-positive status (P = 0.027) and triple-negative breast cancer (TNBC) (P = 0.006). Multiple logistic regression analysis showed that pCR was correlated with HER2 status (odds ratio 26.589, confidence interval [CI] =1.606-44.190), P = 0.022. Of the seven patients found to have pCR, six patients (85.7%) were treated with taxol-containing regimen. The other parameters that were correlated with pCR are TNBC and estrogen receptor/progesterone receptor status. Tumor size, Ki-67 value, and grade of the tumor were not correlated with clinical response. CONCLUSION: Molecular subtype in breast cancer is an effective factor for predicting response to neoadjuvant chemotherapy. HER2-positive status was associated with high Ki-67 and high clinical and pathological response rate. Taxol needs to be added in neoadjuvant chemotherapy to improve pCR. Luminal subtypes respond poorly to chemotherapy.