Nationwide cohort study of statin initiation and mortality after colorectal cancer treatment in South Korea

Observational studies have suggested improved survival among patients with colorectal cancer (CRC) who start statin therapy after diagnosis, but such studies are vulnerable to time-related biases and informative censoring. A nationwide cohort study using Korean National Health Insurance Service claims for 2005 through 2015 aimed to estimate the association between statin initiation after CRC treatment and CRC-specific and all-cause mortality using target trial emulation. Eilgible adults had newly diagnosed CRC and no statin prescriptions in the prior 6 months. Time zero was the date of first CRC treatment. Among 88 516 patients (mean age 62.7 years; SD 11.7; 63.7 male), 2071 initiated statins and 86 445 did not. Statin initiation was associated with modestly lower CRC-specific mortality (HR 0.95; 95% CI 0.92-0.99) and non-significantly lower all-cause mortality (0.96; 0.93-1.00). The 60-months absolute differences in CRC-specific were small. In the positive-control cohort with ischemic heart disease, statin initiation was associated with lower all-cause but not cardiovascular disease-specific mortality. The authors conclude that these findings suggest that posttreatment statin initiation is unlikely to confer a large survival benefit in patients with CRC.