Association of relative resection volume with patient-reported outcomes applying different levels of oncoplastic breast conserving surgery - A retrospective cohort study

Introduction: The American Society of Breast Surgeons (ASBrS) recently classified oncoplastic breast conserving surgery (OBCS) into two levels. The association of resection ratio during OBCS with patient-reported outcomes (PRO) is unclear. Materials and methods: Patients with stage 0-III breast cancer undergoing OBCS between 01/2011-04/2023 at a Swiss university hospital, who completed at least one postoperative BREAST-Q PRO questionnaire were identified from a prospectively maintained institutional database. Outcomes included differences in PROs between patients after ASBrS level I (<20 % of breast tissue removed) versus level II surgery (20-50 %). Results: Of 202 eligible patients, 129 (63.9 %) underwent level I OBCS, and 73 (36.1 %) level II. Six patients (3.0 %) who underwent completion mastectomy were excluded. The median time to final PROs was 25.4 months. Patients undergoing ASBrS level II surgery were more frequently affected by delayed wound healing (p < 0.001). ASBrS level was not found to independently predict any BreastQ domain. However, delayed wound healing was shown to reduce short-term physical well-being (estimated difference -26.27, 95 % confidence interval [CI] -39.33 to -13.22, p < 0.001). Higher age was associated with improved PROs. Conclusion: ASBrS level II surgery allows the removal of larger tumors without impairing PROs. Preventive measures for delayed wound healing and close postoperative follow-up to promptly treat wound healing disorders may avoid short-term reductions in physical well-being.