Abstract P2-07-02: Effects of different duration of prophylactic antibiotic use on unplanned reoperation in breast cancer patients undergoing implant-based breast reconstruction: A retrospective study with overlap weighting analysis

Abstract Background: Some special consensus recommended the duration of perioperative antibiotic prophylaxis was within 24 hours postoperatively in breast cancer undergoing postmastectomy implant breast reconstruction. However, surgeons in practice favored to prolong the duration. The aim of this study was to estimate the effects of duration of antibiotics on major adverse outcomes in real clinical practice setting with diverse population using overlap weighting model. Methods: In this retrospective study, patients with breast cancer undergoing breast implant reconstructions were collected in Fudan University Shanghai Cancer Center from 1 January 2008 to 31 December 2021. Cases were divided into two groups according to the duration of perioperative antibiotic prophylaxis: short-term group (≤ 24 hours) and long-term group (>24 and≤48 hours). The primary outcomes were unplanned reoperations and complication-related unplanned reoperations. Unplanned reoperation was defined as debridement, expander removal without prosthesis implantation, expander removal and expander implantation, prosthesis removal and prosthesis implantation, prosthesis removal, prosthesis removal and expander implantation. By reviewing the patients’ detailed medical history, all unplanned reoperations were divided into non-complication-related unplanned reoperations and complication-related unplanned reoperations. Non-complication-related unplanned reoperations included: patients voluntarily gave up continuing reconstruction, suspected recurrence of cancer, changed reconstruction methods, unsatisfactory appearance, and unknown reasons. Complication-related unplanned reoperations included: infection, exposure of prosthesis or expander, poor wound healing, rupture of expander, necrosis of skin flap, bleeding. The secondary outcomes were infections that required intervention. It was defined as both met with white blood cells elevation and physician antibiotic prescription during outpatient follow-up. To adjust confounders, propensity score overlap weighting was used, and subgroup analysis and sensitive test were conducted to demonstrate the robustness of results. A P value less than 0.05 was considered statistically significant. Results: In 4367 cases of unilateral implant reconstructions, 4128 (95%) were included in this study. Among them, 1689 were expander implantation, 1124 were prosthesis implantation and 1315 were expander removal and prosthetic implantation. At inclusion, only 283 cases (6.9%) received antibiotics prophylaxis ≤24 hours, 3090 cases (74.9%) with duration >24 and≤48 hours, and 755 cases (18.3%) with duration >48 hours. Of them, 230 cases (5.6%) underwent unplanned reoperation, including 131 (3.2%) complication-related unplanned reoperations, and 99 (2.4%) non-complication-related unplanned reoperations. And there were 110 cases (2.7%) with infections that required intervention. In unweighted or weighted data set, short-term antibiotic use did not significantly increase the risk of adverse outcomes, including unplanned reoperation, complication-related unplanned reoperation, and infection required intervention, compared with long-term antibiotic use with or without patients with duration more than 48 hours. Most subgroup analysis showed no evidence of heterogeneity of the effects of duration of antibiotic use on adverse outcomes. Conclusion: In clinical setting with diverse population, prolong antibiotic prophylaxis with more than 24 hours is not necessary to reduce major adverse outcomes, even in some critical conditions. Appropriating and accessible prophylactic initiatives should be developed and implemented with shorten the duration of antibiotic prophylaxis and minimized adverse outcomes. Key words: perioperative antibiotic prophylaxis, breast cancer, postmastectomy implant reconstruction, unplanned reoperation Citation Format: Zeqing Li, Jiajian Chen, Shuang Hao, A-Yong Cao, Xiaoyan Huang, Zhiming Shao, Jiong Wu. Effects of different duration of prophylactic antibiotic use on unplanned reoperation in breast cancer patients undergoing implant-based breast reconstruction: A retrospective study with overlap weighting analysis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-07-02.