Increased kidney cancer risk in diabetes mellitus patients: a population-based cohort study in Lithuania.

ABSTRACT

BACKGROUND: Diabetes is associated with increased risk of various cancers but its association with kidney cancer is unclear. The objective of this study was to evaluate the association between T2DM with or without metformin use and the risk of kidney cancer in a population-based national cohort in Lithuania. METHODS: The cohort was composed of diabetic patients identified in the NHIF database during 2000-2012. Cancer cases were identified by record linkage with the national Cancer Registry. Standardized incidence ratios (SIRs) for kidney cancer as a ratio of observed number of cancer cases in diabetic patients to the expected number of cancer cases in the underlying general population were calculated. RESULTS: T2DM patients (11,592) between 2000 and 2012 were identified. Overall, 598 cases of primary kidney cancer were identified versus 393.95 expected yielding an overall SIR of 1.52 (95% CI 1.40-1.64). Significantly higher risk was found in males and females. Significantly higher risk of kidney cancer was also found in both metformin users and never-users' groups (SIRs 1.45, 95% CI 1.33-1.60 and 1.78 95% CI 1.50-2.12, respectively). CONCLUSIONS: The patients with T2DM have higher risk for kidney cancer compared with the general Lithuanian population.