D33. Oncoplastic Breast Surgery: Optimizing Resection Margins in Addition to Aesthetic Outcomes

PURPOSE - Oncoplastic breast surgery has been shown to achieve better aesthetic outcomes than lumpectomy alone. However, there is a dearth of literature on whether oncoplastic surgery also provides oncologic benefit. This is important to consider given that despite advances in tumor imaging and localization, reported rates of positive margins after lumpectomy range anywhere from 10% to 60% depending on cancer type. This study aims to determine whether oncoplastic surgery improves resection margins compared to lumpectomy alone. METHODS: This is a retrospective cohort investigation of women who underwent breast conserving therapy (lumpectomy alone versus oncoplastic breast surgery) at our institution between 2010-2023. The rate of margin re-excision within 6 months of the index procedure was compared between cohorts. RESULTS: Of 4,673 study patients, 4,164 (89.6%) underwent lumpectomy alone and 488 (10.4%) underwent oncoplastic breast surgery. Oncoplastic surgery became significantly more prevalent over the course of the study period (p=0.04). The overall re-excision rate was higher in the lumpectomy cohort that in the oncoplastic surgery cohort (17% vs. 13%). After adjusting for potential confounders using propensity score matching, oncoplastic surgery was associated with significantly lower odds of re-excision (OR 0.7, 95% confidence interval 0.4-1.0, p=0.05). CONCLUSIONS: Oncoplastic surgery may help to better achieve clear surgical margins compared to lumpectomy alone by providing a wider excision without compromising breast aesthetics. Furthermore, we found that an increasing number of patients are choosing an oncoplastic approach. As such, whenever possible, efforts should be made to offer oncoplastic surgery to appropriate patients.