Do postoperative infectious complications really affect long‐term survival in colorectal cancer surgery? A multicenter retrospective cohort study

AIM: To investigate the impact of postoperative infection (PI), surgical site infection, and remote infection (RI), on long‐term outcomes in patients with colorectal cancer (CRC). METHODS: The Japan Society for Surgical Infection conducted a multicenter retrospective cohort study involving 1817 curative stage I/II/III CRC patients from April 2013 to March 2015. Patients were divided into the No‐PI group and the PI group. We examined the association between PI and oncological outcomes for cancer‐specific survival (CSS) and overall survival (OS) using Cox proportional hazards models and propensity score matching. RESULTS: Two hundred and ninety‐nine patients (16.5%) had PIs. The 5‐year CSS and OS rates in the No‐PI and PI groups were 92.8% and 87.6%, and 87.4% and 83.8%, respectively. Both the Cox proportional hazards models and propensity score matching demonstrated a significantly worse prognosis in the PI group than that in the No‐PI group for CSS (hazard ratio: 1.60; 95% confidence interval: 1.10‐2.34; P = .015 and P = .031, respectively) but not for OS. RI and the PI severity were not associated with oncological outcomes. The presence of PI abolished the survival benefit of adjuvant chemotherapy. CONCLUSIONS: These results suggest that PI after curative CRC surgery is associated with impaired oncological outcomes. This survival disadvantage of PI was primarily derived from surgical site infection, not RI, and PI induced lower efficacy of adjuvant chemotherapy. Strategies to prevent PI and implement appropriate postoperative treatment may improve the quality of care and oncological outcomes in patients undergoing curative CRC surgery.