Association between statins and incidence of cancer in patients with dyslipidemia using large-scale health insurance claims data.

Recent experimental studies have examined the efficacy of statins in preventing cancer, but the findings of clinical studies are inconsistent, and studies on Japanese patients are limited. This study aimed to clarify the association between statins and cancer risk among Japanese patients. We conducted a large population-based retrospective cohort study using the Japanese health insurance claims database, including patients newly diagnosed with dyslipidemia between 2006 and 2015. Patients who were on newly prescribed statins during the study period were designated as statin users. They were matched 1:1 with randomly selected drug non-users who were not prescribed drugs for dyslipidemia according to age, sex, and year of first diagnosis of dyslipidemia. There were 23,746 patients in each group. The mean duration of follow-up for statin users and drug non-users was approximately 2 years. Using a Cox proportional hazards model, significant reduction in cancer risk was observed in statin users compared with that in drug non-users (adjusted HR = 0.84, 95% CI = 0.72-0.97; adjusted for patient background factors). The results of subgroup analyses suggested that prescribed statins reduced the incidence of cancer of the digestive organs (adjusted HR = 0.79, 95% CI = 0.63-0.99) as well as reduced cancer risk in patients with non-smokers. Our results suggest that statin use may reduce cancer risk in patients with dyslipidemia.