Risk Factors for Excess Mortality in the First Year After Curative Surgery for Colorectal Cancer

Background Thirty-day mortality after surgery for colorectal cancer may vastly underestimate 1-year mortality. This study aimed to quantify the excess mortality in the first postoperative year of stage I–III colorectal cancer patients and to identify risk factors for excess mortality. Methods All 2,131 patients who were operated with curative intent for stage I–III colorectal cancer in the western region of the Netherlands between January 1, 2006, and December 31, 2008, were analyzed. Thirty-day mortality and relative survival were calculated. In addition, relative excess risk (RER) of death was estimated by a multivariable model. Results Thirty-day mortality was 4.9%. One-year mortality was 12.4%. Risk factors for excess mortality in the first postoperative year for colon cancer patients were emergency surgery (excess mortality 29.7%, RER 2.5, 95% confidence interval 2.5–5.0), a Charlson score of >1 (excess mortality 12.6%, RER 2.3, 95% confidence interval 1.5–3.7), stage II or III disease (excess mortality 14.9%, RER 3.9, 95% confidence interval 1.9–8.1), and postoperative adverse events (excess mortality 22.6%, RER 2.1, 95% confidence interval 1.4–3.2). Conclusions The 30-day mortality rate highly underestimates the risk of dying in the first year after surgery, with excess 1-year mortality rates varying from 15 to 30%. This excess mortality was especially prominent in patients with comorbidities, higher stages of disease, emergency surgery, and postoperative surgical complications.