Clinical usefulness of AJCC response criteria for neoadjuvant chemotherapy in breast cancer

Purpose: Recently, the American Joint Committee on Cancer (AJCC) 7th edition proposed new response criteria for neoadjuvant chemotherapy (NAC) in breast cancer. The purpose of this study was to evaluate the clinical usefulness of AJCC response criteria. Methods: A total of 398 consecutive stage II or III breast cancer patients who received NAC were enrolled in this study. AJCC response criteria were as follows: (1) complete response (CR) - absence of invasive carcinoma in the breast and node; (2) partial response (PR) - decrease in either or both T or N stage; (3) no response (NR) - no change or increase in either or both T or N stage. Results: Complete response, PR, and NR by AJCC criteria were 9.8, 59.3, and 30.7 %, respectively. Among the 398 patients, 337 patients were available for both paired pre- and post- breast MRI and chest CT. AJCC response criteria were significantly associated with RECIST criteria (P < 0.001). AJCC response was significantly associated with relapse-free survival (RFS) and overall survival (OS). The 5-year RFS rates were 89.6 % in CR, 74.1 % in PR, and 62.6 % in NR (P = 0.002). The 5-year OS rates were 97.4 % in CR, 88.6 % in PR, and 78.3 % in NR (P = 0.012). When adjusting potential prognostic factors, AJCC response was independently associated with RFS and OS. Conclusions: AJCC response criteria for NAC in breast cancer have clinical usefulness in evaluating response of NAC, as well as predicting survival. AJCC response criteria can discriminate among patient subgroups with respect to survival.