Factors that predict pathologic complete response in patients receiving neoadjuvant chemotherapy for locally advanced breast cancer.

Abstract

e11588 Background: Locally advanced breast cancer (LABC) accounts for 30-60% of all breast cancer patients presenting to the public hospitals in India. The neoadjuvant chemotherapy is reported to achieve a pathological complete response (pCR) rate of 35-60% depending on the receptor subsets and the chemotherapeutic drugs employed. The patients who achieve a pCR are expected to do better in terms of progression free survival. Hence we reviewed our data base to know pCR rates, to compare pCR rates among various receptor subgroups, and to determine the factors which predict pCR. Methods: All patients with LABC (defined as Stage III, AJCC, 7th edition, 2010) and agreed by the hospital tumor board to receive preoperative chemotherapy were included. At each visit, clinical response was assessed according to RECIST criteria. Re-staging work up and mammography were done prior to surgery. Results: Total 84 patients received preoperative chemotherapy. Most common regimen used was 4 courses of AC followed by 4 courses of 3 weekly paclitaxel. Two patients developed systemic metastasis during chemotherapy and were not considered for surgery. Median age was 46 years (ranged from 28 to 66), 46 patients were premenopausal, and 43 % of the tumors were hormone receptor negative. Her 2nu amplification defined as immunohistochemistry 3 + or FISH positive was seen in 27% of patients. Thirty nine patients were stage IIIB, 38 were III A and 5 were IIIC. Total 72 patients completed full course of chemotherapy before surgery. Clinical response was complete in 26, partial in 52, 3 had local progression, one stable and two patient developed distant metastasis (not considered for surgery). Forty eight patients underwent modified radical mastectomy and breast could be conserved in 34 patients. The pCR rate was 36%. Of all the factors (cT status, hormone receptor status, menopausal status, age) cT status was found to be statistically significant factor to predict pCR (p<0.005). Conclusions: Overall pCR rate in the study was 36%, maximum response was noted in ER/PR negative, Her 2nu positive subset. Only factor which was found to be associated with pCR on univariate analysis was cT size.