Abstract P3-12-07: Conservative breast reconstruction: Outcomes of 146 consecutive cases of prepectoral, subcutaneous implant-based breast reconstruction in a single-Institution series

Abstract Aims. To evaluate acute and late toxicity-related factors among breast cancer (BC) patients who underwent prepectoral breast reconstruction (BR). Methods. We performed a retrospective analysis of BC patients who underwent therapeutic or prophylactic mastectomy from October 2012 to May 2016 at our Center. We recorded individual patient-related features (i.e. age, body mass index [BMI], smoke-history, comorbidity, BRCA-carrier), BC-related treatments characteristics (i.e. axillary surgery, adjuvant radiotherapy [RT], adjuvant chemotherapy, primary systemic therapy [PST], endocrine therapy, and use of trastuzumab). Toxicity profile was evaluated in terms of complications related to BR; we recorded acute and late toxicity data and prosthesis/implant explant rate. Results. We analyzed 146 consecutive BC patients treated with subcutaneous BR, 117 therapeutic and 29 prophylactic mastectomies. Thirty-seven patients received postmastectomy RT. Significant factors related to acute toxicity were: previous RT (34.5% [RT] vs 8.5% [no RT]; p=0.001), BMI (31.3% [BMI ≥25] vs 8.8% [<25]; p=0.003), previous breast surgery (22.2% [surgery] vs 8.7% [no surgery]; p=0.027), and diabetes (100% [diabetes] vs 11.9% [no diabetes]; p=0.002). Factors significantly correlated to implant/prosthesis explant were: current or previous smoking exposition (13.8% [smokers] vs 2.6% [non-smokers]; p=0.029) and PST (18.8% [PST] vs 3.5% [no PST]; p=0.022); axillary lymph node dissection (ALND) was significantly related to late toxicity (5.7% [ALND] vs 0%; p=0.04). At a 3-year median follow up, three deaths, five locoregional recurrences (LRR), and fourteen distant metastasis (DM) occurred among 117 patients treated by therapeutic mastectomy. Overall survival was 78.1%, LRR free-survival was 95%, and DM free-survival was 71.6%. Postmastectomy RT was not significantly related to acute, late toxicity, and explant occurrence. Conclusions. In our experience prepectoral subcutaneous implant-based BR is a safe and effective approach, with low rates of acute toxicity. Major risk factors were evidenced for patients previously treated with RT or surgery, and in case of diabetes or BMI ≥25; postmastectomy RT seems not to be related to higher rate of toxicity. ALND seems to be the only factor significantly related to late toxicity. PST, and smoking exposition were significantly associated with higher rate of implant/prosthesis explant. However, further investigations and mature follow-up are warranted to confirm these encouraging results. Citation Format: Meattini I, Bernini M, Saieva C, Desideri I, Scotti V, Salvestrini V, Visani L, Mariotti M, Delli Paoli C, Olmetto E, Maragna V, Orzalesi L, Sanchez L, Nori J, Bianchi S, Livi L. Conservative breast reconstruction: Outcomes of 146 consecutive cases of prepectoral, subcutaneous implant-based breast reconstruction in a single-Institution series [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-12-07.