Abstract / Summary
Abstract Postoperative sepsis is a rare but life-threatening complication after breast cancer surgery. Although infection risk in breast surgery is generally low, cancer-related immune dysregulation combined with surgical stress may increase susceptibility, yet large-scale data on incidence, risk factors, and outcomes remain limited. We conducted a retrospective analysis of the ACS-NSQIP database (2008–2022). Adult female patients undergoing breast cancer surgery were included. The primary outcome was ACS-NSQIP-coded 30-day postoperative sepsis; septic shock was analyzed separately and descriptively. Multivariable logistic regression was used to evaluate factors associated with postoperative sepsis. Model performance was assessed by area under the receiver operating characteristic curve (AUC) with bootstrap correction for optimism and compared with machine-learning approaches trained with explicit handling of class imbalance. Among 328,292 patients (47.8% partial, 38.6% simple, 13.6% radical mastectomy), sepsis occurred in 838 (0.26%), with incidence increasing across procedure categories (0.08% vs. 0.40% vs. 0.46%; p < 0.001). Patients with sepsis had markedly higher rates of reoperation (46.5% vs. 4.0%) and unplanned readmission (73.7% vs. 2.1%; both p < 0.001). The strongest adjusted associations with postoperative sepsis were observed for prior sepsis (aOR 4.51), functional dependence (aOR 3.80), and ASA class III (aOR 3.16; all p < 0.001). Reconstruction was also associated with higher adjusted odds of sepsis, with aORs of 2.15 for autologous and 1.59 for implant-based reconstruction. The model showed good discrimination (apparent AUC 0.752; optimism-corrected AUC 0.746) and was well calibrated (bootstrap-corrected calibration slope 0.967). No machine-learning approach outperformed logistic regression on the held-out test set (DeLong p = 0.077–0.409). Sepsis after breast cancer surgery is uncommon but clinically significant, with incidence increasing across procedure categories. Reconstruction, particularly autologous reconstruction, was associated with sepsis after adjustment for measured covariates. Because oncologic and treatment-related variables are not captured in ACS-NSQIP, this association should be interpreted as observational rather than causal. These findings may inform individualized preoperative risk assessment and counseling.