987 – Oncoplastic breast-conserving surgery enables wider resections without compromising oncologic outcomes in a public hospital cohort

Abstract

Introduction: Breast-conserving surgery (BCS) combined with adjuvant therapy is an established oncologically safe
approach for breast cancer treatment. However, conventional techniques may lead to suboptimal cosmetic outcomes,
particularly in cases requiring larger resections. Oncoplastic surgery was developed to allow wider excisions while preserving breast shape.
Objective: This study aimed to evaluate the oncologic safety of oncoplastic BCS compared to standard BCS in a public
hospital.
Methods: This retrospective cohort study included 142 women with breast cancer who underwent BCS between July
2023 and July 2025 at a municipal public hospital in São Paulo, Brazil. Clinical and pathological data were obtained from
medical records. Patients were divided into two groups according to surgical technique: standard BCS and oncoplastic
BCS. The primary outcome was positive margin rate. Secondary outcomes included specimen weight and postoperative
complications.
Results: Oncoplastic BCS was associated with significantly larger resection weights (median 123 g vs. 31 g; p<0.001), with
no difference in complication rates (7.5% vs. 4.9%; p=0.687). Patients undergoing oncoplastic surgery were significantly
younger (57.0 years, standard deviation ±13.6 vs. 62.7 years ±11.6; p=0.021) and presented with more advanced tumors
(p<0.001), with a higher proportion of T2+ (80.0%) and T3–T4 disease (20.0%). Despite this, negative margins were achieved
in 90% of cases at initial surgery. The positive margin rate was 10.0% (95% confidence interval [CI] 4.0–23.1%), consistent
with rates reported in the literature. No positive margins were observed among patients with T3–T4 tumors.
Conclusion: Oncoplastic BCS allowed wider resections without increasing complications and achieved acceptable margin rates, even in patients with more advanced disease. These findings support oncoplastic BCS as a safe and effective
breast-preserving alternative to mastectomy, particularly in patients with unfavorable tumor-to-breast ratios in the public health setting.
Ethics: Research Ethics Committee Approval (CAAE 28003220.2.0000.0071).