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 – -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.