Background Postsurgical bleeding is a major complication of mastectomy in patients with breast cancer. However, the risk factors for postsurgical bleeding have not been well studied. Although obesity or reduced skeletal muscle mass is an indicator of cancer surgery complications, its impact on postsurgical bleeding after mastectomy remains unknown.Methods In total, 563 patients with breast cancer who underwent mastectomy were included in this study. We evaluated the preoperative body mass index (BMI), skeletal muscle index (SMI), and SMI-to-BMI ratio and analyzed the association between these values and the incidence of postsurgical bleeding.Results Postsurgical bleeding occurred in 33 (5.6%) patients. Mean BMI was significantly higher in the bleeding group (26.3 ± 4.7) than in the no bleeding group (23.0 ± 4.1) (p p = 0.08). The bleeding group had significantly lower SMI-to-BMI ratio (1.71 ± 0.16) than the no bleeding group (2.10 ± 0.23) (p p Conclusions SMI-to-BMI ratio is a superior predictive factor of postsurgical bleeding after mastectomy to either BMI or SMI alone.
