Factors Impacting Pathologic Complete Response after Neoadjuvant Chemotherapy in Breast Cancer: A Single-Center Study

Background: Neoadjuvant chemotherapy is the standard treatment for patients with locally advanced breast cancer which was recently introduced for operable breast cancer especially to achieve negative margins in breast conservation. Several studies have shown that Pathologic complete response (pCR) after neoadjuvant chemotherapy increases survival rate. The aim of this study therefore, was to evaluate the rate of pathologic complete response and its effective factors in breast cancer research center (BCRC). Methods: During a cross-sectional study, 179 patients with stage I to III breast cancer, who received neoadjuvant chemotherapy in breast cancer research center from 1997 to 2014, were included. Cases with pathologic complete response were defined as no tumor residue in the breast tissue and axillary region. This group of patients was compared with patients who had residual tumor at pathology. Data were analyzed by descriptive and inferential statistics using SPSS 19. Results: The mean age of patients was 45.4 years. Thirty-four patients (19%) were identified in the pathological complete response group (pCR). There was no significant difference between the pCR and non-pCR groups with respect to Age, Menopausal status, Family history of breast cancer, Tumor size, Histological type, Hormone receptors, Her-2neu and Phenotypic subtypes. However, ki67 index was significantly different between the two groups of patients, indicating that in patients with Ki67 of more than 40, pCR was the most observed (P = 0.01). Conclusions: This study showed that among the demographic, clinical, pathological and therapeutic factors, Ki67 can be a predicting factor for pathologic complete response after neoadjuvant chemotherapy.