Long-Term Safety of Level II Oncoplastic Surgery after Neoadjuvant Treatment for Locally Advanced Breast Cancer: A 20-Year Experience.

Background: Oncoplastic surgery (OPS) reliability in the post-neoadjuvant chemotherapy (NACT) setting is still debated due to weak scientific evidences in such scenarios. Methods: Our analysis aims to report results obtained in a retrospective series of 111 patients consecutively treated with level II OPS after NACT at the Multidisciplinary Breast Center of the Fondazione Policlinico Universitario Agostino Gemelli IRCCS between 1998 and 2018. The surgical endpoints were the mean specimen volume, rates of positive margins (PMR), re-excision (RR), conversion to mastectomy (CMR), and complications (CR). The oncological endpoints were overall survival (OS), disease-free survival (DFS), and local recurrence (LR). To evaluate the impact of NACT on surgical and oncological outcomes at 302 months, we conducted a propensity score matching, pairing patients in post-NACT and upfront surgery groups. Results: The mean sample volume was 390,796 mm 3 . We registered a 3.6% of PMR, 1.8% RR, 0.9% CMR, 5% CR. The 10-year OS and 10-year DFS with a median follow-up of 88 months (6-302) were 79% and 76%, respectively, with an LR recurrence rate of 5%. The post-NACT group received significantly larger excised volumes and lower PMR. NACT did not affect surgical and oncological outcomes. Conclusions: Level II OPS can be considered a reliable alternative to mastectomy even in the post-NACT setting.