Anastomotic leak after surgery for colon cancer and effect on long‐term survival

Abstract Aim An anastomotic leak after surgery for colon cancer is a recognized complication but how it may adversely affect long‐term survival is less clear because data are scarce. The aim of the study was to investigate the long‐term impact of Grade C anastomotic leak in a large, population‐based cohort. Method Data on patients undergoing resection for Stage I–III colon cancer between 2008 and 2012 were collected from the Swedish, Norwegian and Danish Colorectal Cancer Registries. Overall relative survival and conditional 5‐year relative survival, under the condition of surviving 1 year, were calculated for all patients and stratified by stage of disease. Results A total of 22 985 patients were analysed. Anastomotic leak occurred in 849 patients (3.7%). Five‐year relative survival in patients with anastomotic leak was 64.7% compared with 87.0% for patients with no leak ( P < 0.001). Five‐year relative survival among the patients who survived the first year was 88.6% vs 81.3% ( P = 0.003). Stratification by cancer stage showed that anastomotic leak was significantly associated with decreased relative survival in patients with Stage III disease ( P = 0.001), but not in patients with Stage I or II ( P = 0.950 and 0.247, respectively). Conclusion Anastomotic leak after surgery for Stage III colon cancer was associated with significantly decreased long‐term relative survival.