D12. Impact of Breast Reconstruction Modality on Breast Cancer Recurrence Detection

PURPOSE: Post-mastectomy reconstruction is not expected to have different oncologic outcomes than mastectomy alone. However, given the disparate masking of the posterior mastectomy margin by various reconstructive modalities, we evaluate the long-term impact of reconstructive choices on oncologic outcomes, including local recurrence rate, time to detection, and size of recurrence, in a single-institution cohort of breast reconstruction patients. METHODS: A retrospective cohort analysis of patients (n=917) with primary breast cancer who underwent either implant-based (n=502) or autologous (n=415) breast reconstruction was conducted. Kaplan-Meier curve estimated cumulative incidence of local breast cancer recurrence over specific time intervals (<13, 13-18, >18 years). A Cox proportion hazard model stratified by time enabled time to recurrence analysis comparing groups. RESULTS: While unsurprising, 52 patients recurred locally (10.3%) with implant-based reconstruction compared to 66 (15.8%) with autologous reconstruction (p=0.02). Average time to detection was 63.5±47.0 months after implant versus 86.5±61.5 after autologous reconstruction (p=0.02). At the time of recurrence, tumor was larger (p=0.01) and of higher stage (p=0.02) in the autologous cohort. Recurrence free survival was initially similar between groups for the first 13 years. Interestingly, it became significantly higher during years 13-18 for the autologous compared to the implant group (82.7% versus 72.8%, p=0.03), but after 18 years, trended lower than implant reconstruction. CONCLUSION: Our findings highlight an interesting but often neglected consideration when selecting breast reconstructive modality. Implant reconstruction may allow for earlier cancer recurrence detection. While there are significant premiums in autologous reconstruction, those patients may warrant increased long-term recurrence surveillance.