Purpose: Breast cancer is the most common type of cancer in women in Brazil and worldwide, corresponding to around 20% of all malignant tumors in women.
Biomarker expression in breast cancer. Correlations with outcome following neoadjuvant chemotherapy
Abstract
Purpose: Breast cancer is the most common type of cancer in women in Brazil and worldwide, corresponding to around 20% of all malignant tumors in women. Neoadjuvant chemotherapy improves survival rates in around 30% of patients with locally advanced disease. This study evaluated biomarker expression in tumor samples and assessed outcome variables following neoadjuvant chemotherapy. Methods: This longitudinal, analytical study included 86 patients of 28 to 80 years of age who were evaluated according to clinical data, histology and laboratory analysis of selected markers. Results: Positivity for estrogen (ER) and progesterone receptors (PR) was 58.54% and 65.79%, respectively. The tumors were predominantly negative for the HER2, CK5/6, EGFR, p53 and Topo II biomarkers and predominantly positive for the Ki-67, PTEN and IGF-1 biomarkers. The results obtained for ER showed associations with PR (p=0.002), Ki-67 (p=0.049), CK5/6 (p=0.027) and p53 (p=0.032). Likewise, there were associations between HER2 and Ki-67 (p=0.028) and between Ki-67 and Topo II (p=0.001). Eighteen patients (20.93%) achieved complete clinical response, while 9 (10.47%) achieved pathologic complete response (pCR). There was an association between pCR and the HER2 (p=0.05) and Topo II (p=0.007) biomarkers. More patients with HER2 tumors (40%) achieved pCR compared to those with the other subtypes, while none of the patients with luminal A tumors achieved pCR (p=0.043). Conclusions: In this study, HER2 and Topo II expression, as well as tumors classified as HER2 subtype or luminal A subtype were predictive of pCR.