Associations between blood cultures after surgery for colorectal cancer and long-term oncological outcomes.

Background Systemic inflammation for colorectal cancer may be associated with an increased risk of recurrence. This study investigated whether a clinically suspected infection, for which blood cultures were sent within 30 days after surgery for colorectal cancer, was associated with long-term oncological outcomes. Methods This register-based national cohort study included all Danish residents undergoing surgery with curative intent for colorectal cancer between January 2003 and December 2013. Patients who developed recurrence or died within 180 days after surgery were not included. Associations between blood cultures taken within 30 days after primary surgery and overall survival, disease-free survival and recurrence-free survival were analysed using Cox regression models adjusted for relevant clinical confounders, including demographic data, cancer stage, co-morbidity, blood transfusion, postoperative complications and adjuvant chemotherapy. Results The study included 21 349 patients, of whom 3390 (15 center dot 9 per cent) had blood cultures taken within 30 days after surgery. Median follow-up was 5 center dot 6 years. Patients who had blood cultures taken had an increased risk of all-cause mortality (hazard ratio (HR) 1 center dot 27, 95 per cent c.i. 1 center dot 20 to 1 center dot 35; P < 0 center dot 001), poorer disease-free survival (HR 1 center dot 22, 1 center dot 16 to 1 center dot 29; P < 0 center dot 001) and higher risk of recurrence (HR 1 center dot 15, 1 center dot 07 to 1 center dot 23; P < 0 center dot 001) than patients who did not have blood cultures taken. Conclusion A clinically suspected infection requiring blood cultures within 30 days of surgery for colorectal cancer was associated with poorer oncological outcomes.