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.