Postoperative complications after colorectal cancer surgery and the association with long-term survival

Background: Complications after colorectal cancer surgery can worsen long-term survival. The aim of this nationwide study was to determine the impact of different types of complications on overall survival (OS) and conditional survival if still alive one year postoperatively (CS-1) after colorectal cancer surgery. Materials and methods: All patients registered in the Dutch ColoRectal Audit after resection of primary colorectal cancer between 2011 and 2017 and with known survival status were included. Multivariable Cox regression models were used to assess the association of complications with OS and CS-1, thereby calculating the Hazard Ratio (HR) with 95% Confidence Interval. Results: 43,908 colon and 16,955 rectal cancer patients were included. Median follow-up time was 66.1 and 66.5 months, respectively. Five-year OS after colon cancer resection was 73.2% without complications, and 65.4% with surgical, 52.9% with non-surgical and 51.8% with combined type of complications (p < 0.001). Corresponding 5-year OS for rectal cancer patients was 76.9%, 72.7%, 64.9%, and 63.2% (p < 0.001). In colon cancer, multivariable analyses revealed HR 1.198 (1.136–1.264) for surgical, HR 1.489 (1.423–1.558) for non-surgical and HR 1.590 (1.505–1.681) for combined type of complications. For rectal cancer, these HRs were 1.193 (1.097–1.2297), 1.456 (1.346–1.329), and 1.489 (1.357–1.633). Surgical complications were associated with worse CS-1 in rectal cancer (HR 1.140 (1.050–1.260), but not in colon cancer (HR 1.007 (0.943–1.075)). Conclusion: Non-surgical complications have higher impact on survival than surgical complications. The impact of surgical complications on survival was still measurable after surviving the first year in rectal cancer but not in colon cancer patients.