The Radiological Response Rate Pattern Is Associated With Recurrence Free Survival in Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy

PURPOSE: The aim of this study was to evaluate the radiological response rate patterns during neoadjuvant chemotherapy (NAC) in patients with breast cancer. METHODS: Patients who underwent NAC with two specific chemotherapy regimens (doxorubicin with cyclophosphamide or doxorubicin with docetaxel) and who underwent a response evaluation every two cycles were included in the study. The initial response ratio was defined as the ratio of the largest tumor diameter at diagnosis to that after two cycles of NAC. The latter response ratio was defined as the ratio between the tumor size after two cycles and that after four cycles of NAC. The radiological response rate pattern was divided into three groups: the fast-to-slow response group (F–S group, initial response ratio > latter response ratio + 20%), slow-to-fast response group (S–F group, latter response ratio > initial response ratio + 20%), and constant response group (less than 20% difference between the initial and latter response ratios). RESULTS: In total, 177 patients were included in the analysis. Forty-two (23.9%) patients were categorized into the F–S group, 26 (14.8%) into the S–F group, and 108 (61.2%) into the constant group. Clinicopathologic factors did not differ according to radiologic response rate patterns. The median follow-up period was 50 months (range, 3–112) months. In the univariate analysis, the F–S group had a significantly worse recurrence-free survival than the S–F and constant groups (hazard ratio [HR], 3.63; 95% confidence interval [CI], 1.05–12.46; p = 0.041). The F–S group also presented with significantly worse survival than the S–F group in the multivariate analysis (HR, 3.45; 95% CI, 1.00–11.89; p = 0.049). CONCLUSION: The F–S group had a poorer survival rate than the S–F group. Radiological response rate patterns may be useful for accurate prognostic assessments, especially when considering post-neoadjuvant therapy.