Abstract Background: Despite the implication of bacterial biofilms in the etiology of capsular contracture, there is limited research on the microbial structure of the biofilm in patients with capsular contracture. Moreover, the potential role of the skin microbiome in capsular contracture remains undefined. Therefore, we conducted this study to characterize the microbiome of the breast capsular contracture by comparing it with the microbiome of biofilms without capsular contracture. We also investigated the associations between the microbial structures of the skin surrounding the breast and those of the breast capsule. Results: We collected 25 capsules, including 14 samples from biofilms without capsular contracture and 11 samples from biofilms with capsular contracture. Beta diversity analysis demonstrated that the microbial structures in biofilms were distinctly different from those in the skin. The microbial composition of the biofilms was more influenced by individual variation than by the progression of the capsular contracture. Biofilms with capsular contracture showed a higher relative abundance of Staphylococcus, correlating positively with total bacterial load. Conclusions: Capsular contracture is associated with an escalation in total bacterial load and an increase in the abundance of opportunistic pathogens, such as Staphylococcus. This comparative analysis of biofilms in contracted breast capsules emphasizes the management of pathogens, considering bacterial load, in the occurrence of capsular contracture. Citation Format: Y. Jung Dug, T. Park, H. Cho, Y. Chang, M. Kim, J. Shin, J. Lee, J. Lee, H. Park, T. Jung. Comparative microbiome analysis of biofilm in contracted breast capsules: a cross-sectional study abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS2-05-10.
Dug et al. (2026) studied this question.