PREDICTING RESPONSE TO NEOADJUVANT CHEMOTHERAPY IN OPERABLE BREAST CANCER: ROLE OF ER, PR, HER2 AND KI-67 INDEX

Abstract

Background: Neoadjuvant (anterior or pre-operative) chemotherapy for operable breast cancer helps in down-staging of the tumor and increases the rate of breast conservation surgery. Factors that identify individuals who benet from chemotherapy have not been clearly established. This study was conducted to assess the role of estrogen receptor, progesterone receptor, HER2 and Ki-67 index in predicting response to a standard anthracycline and taxane-based chemotherapy. Methods: The study included 62 women with clinical tumor stage 1-3 and nodal stage 0 or 1. All women received preoperative anthracycline and taxane-based chemotherapy followed by surgery. Clinical and pathological response was assessed using World Health Organization (UICC) and Chevallier's criteria respectively. Results: Clinical and pathological complete response rates were 40.3% and 17.7% respectively. The pathological complete response was highest in HER2-enriched patients (45.45%) while basal-like and luminal B subtypes accounted for 27.27% each. Among those that achieved pathological complete response, 90% had Ki-67 >20, 81.8% had grade 3, 72.7% had ER negative status, 81.8% had PR negative status, 63.6% had HER2 positive status. However, there was no statistically signicant association between preoperative clinical tumor size(p=0.98), ER(p=0.053), PR(p=0.17), HER2(p=0.17), Ki-67 index(p=0.26) and pathological complete response. Conclusion: Ahigh pathological complete response was observed in tumors with high grade, high proliferative activity (high Ki-67), ER/PR negative status, HER2 over-expressing tumors and aggressive molecular subtypes such as basal-like and HER2-enriched breast cancer. However, none of these pre-chemotherapy factors showed statistically signicant association with pathological complete response.