Clinical response assessment after 2 cycles of neoadjuvant chemotherapy for primary breast cancer fails to predict for final clinical response, but does predict for pathological complete response

Abstract

667 Background: Neoadjuvant chemotherapy (NC) is increasingly being used for large primary breast carcinomas. Clinical trials have established its role in improving breast-conserving surgery (BCS) rates and have shown that complete pathological response (pCR) is associated with improved survival. Early evaluation of response is important for selecting patients with possible worse outcomes, who may benefit from alternative treatments. Methods: 107 women received NC for large operable breast cancers (T2–4, N1–2, M0). Patients received 6 cycles of FEC chemotherapy (5-FU 500mg/m2, epirubicin 75mg/m2, cyclophosphamide 500mg/m2 every 21 days) prior to a planned operation. Clinical response was recorded at baseline, after 2 cycles of NC and on completion of 6 cycles. Baseline and completion ultrasound and/or mammography were performed and a pathological assessment of response was made in those patients who underwent surgery. Results: Median age was 50 (range= 29–78). Overall clinical response rate after 2 cycles of chemotherapy was 59.8% (64/107) and after 6 cycles was 84.1% (90/107). 56 patients (52.3%) underwent BCS, 37 (34.6%) mastectomy and 14 (13.1%) no operation. Overall pCR rate was 15.0% (16/107). Of the 43 patients who failed to respond clinically after 2 cycles, 27 (62.8%) went on to exhibit a clinical response on completion of chemotherapy. 3 (7.0%) patients went on to have a complete clinical response and 21 (48.8%) underwent BCS. However, none of these 43 patients demonstrated a pCR. Conclusions: Lack of clinical response after 2 cycles of neoadjuvant chemotherapy does not preclude clinical response after further treatment with the same schedule, and many women will have sufficient down-staging to enable breast-conserving surgery. However, a pathological complete response is unlikely if no clinical response is observed after 2 cycles. No significant financial relationships to disclose.