Examining the association between statins and lung cancer incidence in patients with type 2 diabetes mellitus

Background/PurposeThe relationship between statin use and lung cancer remains unclear. Patients with diabetes mellitus, who are at higher risks for both cancer and atherosclerosis, are usually indicated for statin use. The objective was to explore the relationship between statins, lung squamous cell carcinoma (SCC), and lung adenocarcinoma incidence in diabetic patients.MethodsA cohort of 596,812 type 2 diabetic patients was identified from the Taiwan National Health Insurance claims database in the year 2000, and followed until the earliest of lung cancer diagnosis, death, or December 31, 2007. A Cox regression model with time-varying statin use was applied to estimate the hazard ratio (HR) of lung cancer incidence comparing use and nonuse of statins. A sensitivity analysis was applied to examine the association after adjustment for smoking effect.ResultsIn the original diabetic cohort, 60,969 statin users and 535,843 statin nonusers were identified. In a median follow-up time of 7.9 years, a total of 1182 incident SCC cases and 2345 adenocarcinoma cases developed. Initial analysis showed a decreased risk of SCC if statins were ever used (HR, 0.69; 95% confidence interval, 0.60–0.81). However, the relative risk would be 0.92 for males and 0.90 for females for statins after adjusting for smoking effect. There was no association between statin use and adenocarcinoma (HR, 0.97; 95% confidence interval, 0.88–1.07), with similar findings after controlling for smoking effect.ConclusionThere is no statistically significant association between statin use with lung cancer incidence in diabetic patients after adjustment for the confounding effect attributed to cigarette smoking.