Major systemic infection following breast cancer surgery and oncological outcomes

Postoperative infections are well-known complications following cancer surgery and are associated with worse oncological outcomes in several cancer types. The influence of major systemic postoperative infections on the risk of breast cancer recurrence remains unexplored. The primary aim of this study was to assess the risk of distant recurrence following major systemic infection. Secondary aims were to assess this risk after other major events such as stroke, myocardial infarction and pulmonary embolism.

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 distant recurrence, whereas secondary outcomes included locoregional recurrence, overall survival, and breast cancer-specific survival.

Among 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 adjusted analyses, major systemic infection was associated with increased risk of distant recurrence (HR 1.23, 95% c.i. 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 locoregional recurrence.

At a median follow-up of 4.8 years, major systemic postoperative infections were associated with an increased risk of distant recurrence, overall death, and breast cancer-specific death, highlighting the importance of timely and effective treatment of postoperative infections.