Comparison of risk of local-regional recurrence after mastectomy or breast conservation therapy for patients treated with neoadjuvant chemotherapy and radiation stratified according to a prognostic index score

Purpose: We previously developed a prognostic index that stratified patients treated with breast conservation therapy (BCT) after neoadjuvant chemotherapy into groups with different risks for local-regional recurrence (LRR). The purpose of this study was to compare the rates of LRR as a function of prognostic index score for patients treated with BCT or mastectomy plus radiation after neoadjuvant chemotherapy. Methods and Materials: We retrospectively analyzed 815 patients treated with neoadjuvant chemotherapy, surgery, and radiation. Patients were assigned an index score from 0 to 4 and given 1 point for the presence of each factor: clinical N2 to N3 disease, lymphovascular invasion, pathologic size >2 cm, and multifocal residual disease. Results: The 10-year LRR rates were very low and similar between the mastectomy and BCT groups for patients with an index score of 0 or 1. For patients with a score of 2, LRR trended lower for those treated with mastectomy vs. BCT (12% vs. 28%, p = 0.28). For patients with a score of 3 to 4, LRR was significantly lower for those treated with mastectomy vs. BCT (19% vs. 61%, p = 0.009). Conclusions: This analysis suggests that BCT can provide excellent local-regional treatment for the vast majority of patients after neoadjuvant chemotherapy. For the few patients with a score of 3 to 4, LRR was >60% after BCT and was <20% with mastectomy. If these findings are confirmed in larger randomized studies, the prognostic index may be useful in helping to select the type of surgical treatment for patients treated with neoadjuvant chemotherapy, surgery, and radiation.