Abstract
BACKGROUND: There is conflicting evidence regarding whether postoperative complications after breast cancer surgery are associated with worse oncological outcome. This study aimed to assess the risk of systemic breast cancer recurrence after surgical site infection and also the impact of surgical site infection on locoregional recurrence, breast cancer-specific survival and overall survival. METHODS: This nationwide cohort study included patients who underwent surgery for primary breast cancer in Sweden between January 2008 and September 2019. The study cohort was identified in the Breast Cancer Database Sweden 3.0, a database linking the National Breast Cancer Quality Register to national population-based healthcare registers held by the National Board of Health and Welfare and Statistics Sweden. The primary exposure was surgical site infection within 90 days from surgery, and the primary outcome was systemic recurrence of breast cancer. Secondary outcomes included locoregional recurrence, overall survival and breast cancer-specific survival. Multivariable Cox regression analysis was performed to assess the association between exposure, predictors and outcomes. RESULTS: Of 82 102 patients included in the study, 15.7% experienced a surgical site infection within 90 days of surgery. Surgical site infection was not significantly associated with systemic recurrence, locoregional recurrence or breast cancer-specific survival after adjustment for confounding variables. Surgical site infection was significantly associated with worse overall survival, but the significant association disappeared in a sensitivity analysis excluding all patients with any kind of malignancy before breast cancer diagnosis. CONCLUSION: Surgical site infection after breast cancer surgery does not significantly increase the risk of systemic recurrence. All possible actions should nevertheless be taken to reduce complication rates.