Association between statin use and the risk of colorectal, liver, and lung cancers: a population-based retrospective cohort study

Background: Epidemiological studies on statin use and cancer risk demonstrated mixed findings. This study aims to i) examine the associations between statin use and the risk of site-specific cancer (colorectal, liver, and lung) incidence; and ii) explore the role of statin use in the presence of other risk factors. Methods: A retrospective cohort study was conducted based on territory-wide electronic health records of Hong Kong between year 2000 and 2021. Patients who had complete lipid profile and no cancer history were identified. The associations between statin use and site-specific cancer incidence were examined using Cox regression. Subgroup analyses were performed by smoking or diabetes status. The interaction patterns between statin use and other risk factors were explored using survival tree analysis. Results: Of the 1,510,263 patients included, 753,504 and 756,759 were statin users and statin non-users respectively. Statin users appeared to have a lower risk of three cancers, with strongest reduction in liver (aHR 0.43, 95%CI:0.40-0.45), followed by lung (aHR 0.73, 95%CI:0.71-0.76) and colorectal (aHR 0.82, 95%CI:0.79-0.85) cancers, when compared to non-users. In subgroup analyses, the risk reduction was greater in diabetes, but similar across smokers and non-smokers. Statin use demonstrated an interaction pattern with smoking across three cancers, and additionally with diabetes in liver cancer. Conclusions: Statin use was associated with a lower risk of several common cancers, particularly in diabetes. Statin use, diabetes, and smoking may collectively exert differential influences on different cancers risk. Impact: Statin use may confer additional protection against several site-specific cancers.