Major systemic infection following breast cancer surgery associated with worse oncological outcomes

Abstract Introduction Postoperative infections are well-known complications following cancer surgery and are associated with worse oncological outcomes in several cancer types. However, the influence of major systemic postoperative infections on the risk of systemic breast cancer recurrence has not been studied. This study primarily aimed to assess the risk of systemic breast cancer recurrence following major systemic infection, and secondarily after other major events (stroke, myocardial infarction, pulmonary embolism). Associations between these events and locoregional recurrence (LRR), overall survival (OS), and breast cancer-specific survival (BCSS) were also evaluated. Method This nationwide cohort study included patients who underwent breast cancer surgery in Sweden between 2008 and 2019. The study cohort was identified using BCBaSe 3.0, a database linking the Swedish National Breast Cancer Quality Register with other national population-based healthcare registers. The primary exposure was major systemic infection within 90 days of surgery, with a secondary analysis of other major events. The primary outcome was systemic breast cancer recurrence, whereas secondary outcomes included LRR, OS, and BCSS. Result Among the 82 102 patients included, 1.8% (n=1461) experienced a major systemic infection and 0.6% (n=516) other major events within 90 days of surgery. In the adjusted analyses, major systemic infection was associated with increased systemic recurrence (HR 1.23, 95% CI 1.07-1.41), overall death (HR 1.47, 1.32-1.64), breast cancer-specific death (HR 1.27, 1.06-1.51), but not with LRR. Discussion Major postoperative systemic infections following breast cancer surgery are associated with systemic recurrence, overall death, and breast cancer-specific death, highlighting the importance of timely and effective treatment of postoperative infections.