Intraoperative and Perioperative Outcomes of Breast-Conserving Surgery After Neoadjuvant Systemic Therapy: A Retrospective Cohort Study.

PURPOSE: Neoadjuvant chemotherapy (NAC), with or without immunotherapy (IO), is increasingly used in patients with breast cancer and may facilitate breast-conserving surgery (BCS). Because these therapies may alter physiologic reserve and perioperative care needs, we evaluated their associations with anesthetic management and postoperative recovery. PATIENTS AND METHODS: This retrospective cohort study included 374 patients with stage II-III breast cancer undergoing BCS at a high-volume ambulatory cancer center. Patients were categorized as receiving NAC, NAC + IO, or no neoadjuvant therapy. Primary outcomes were use of general anesthesia (GA) and postanesthesia care unit length of stay (PACU LOS). Multivariable models adjusted for age, body mass index, receptor subtype, tumor stage, and nodal status; the PACU LOS model additionally adjusted for surgery start time. Secondary outcomes included intraoperative propofol and opioid dosing per surgical hour and 30-day postoperative adverse events. RESULTS: NAC was associated with a 29% higher adjusted probability of GA use (95% confidence interval [CI], 15%-43%) and a 1.4-h longer PACU LOS (P = .001). Among patients receiving NAC, IO was associated with an 18% lower adjusted probability of GA use (95% CI, 3.1%-33%) and a 0.96-h shorter PACU LOS (P = .031). Intraoperative opioid requirements and 30-day postoperative adverse events did not differ meaningfully across treatment groups. Differences in propofol dosing were statistically significant but modest. CONCLUSION: Neoadjuvant treatment exposure was associated with differences in anesthetic approach and postoperative recovery despite low complication rates. These findings support treatment-informed perioperative planning and multidisciplinary coordination for patients undergoing BCS.