Post-Operative Outcomes Across the Levels of Oncoplastic Breast Surgery According to the American Society of Breast Surgeons Oncoplastic Surgery Definition and Classification System

Introduction: Breast cancer survival rates are improving, increasing focus on post-treatment quality of life. Oncoplastic breast surgery (OPS), which combines plastic and reconstructive techniques during breast conservation surgery, has emerged as an important approach to optimize both oncologic safety and cosmetic outcomes. However, data comparing complication rates across different OPS levels are limited. Methods: We conducted a retrospective cohort study using the ACS-NSQIP database (2007−2020) to analyze OPS outcomes using the American Society of Breast Surgeons oncoplastic surgery classification system. OPS techniques are categorized into Level-1, Level-2, and volume-replacement (VR) procedures. Post-operative complications were assessed within 30 days. Results: A total of 9647 patients underwent OPS between 2007 and 2020: 3917 (40.6%) Level-1, 5078 (52.6%) Level-2, and 652 (6.8%) VR surgeries. Mean age differed across groups (61.7, 60.4, and 56.9 years for Level-1, Level-2, and VR, respectively; p < 0.001). Overall complication rates were 3.8% for Level-1, 5.2% for Level-2, and 4.8% for VR, with wound complications more frequent in Level-2 procedures (3.3% vs. 1.7% for Level-1). Compared to Level-1, Level-2 OPS had higher odds of wound complications (OR = 1.472, 95% CI: 1.095–1.979), while VR procedures had lower odds than Level-2 (OR = 0.525, 95% CI: 0.305–0.902), driven mainly by wound dehiscence and superficial surgical site infections, respectively. Operative times increased with complexity (77.7, 110.6, and 171.7 min for Level-1, Level-2, and VR), and length of stay was longest for VR procedures (0.89 vs. 0.05 days for Level-1). BMI ≥ 30 (overall complications, OR = 1.485, 95% CI: 1.203–1.833; p < 0.001; wound complications, OR = 2.202, 95% CI: 1.642–2.951; p < 0.001) and diabetes (overall complications, OR = 1.311, 95% CI: 1.011–1.700; p = 0.041) were independently associated with complications, while smoking was not. VR procedures had lower odds of superficial surgical site infections compared to Level-2 (OR = 0.379, 95% CI: 0.186–0.760; p = 0.006). Level-2 and VR procedures had higher odds of wound dehiscence compared to Level-1 (OR = 1.223, 95% CI: 1.015–1.335; p = 0.039 and OR = 4.274, 95% CI: 1.880–12.154; p = 0.004, respectively). Conclusion: The ASBrS classification system predicts post-operative complications and operative times in OPS. More complex procedures, such as Level-2 OPS, have higher wound complication rates and longer operative times. BMI ≥ 30 and diabetes increase risk, while smoking appears less impactful. VR OPS may be advantageous in high-BMI patients. These findings support surgical planning, patient counseling, and shared decision-making.