Abstract
AIMS/INTRODUCTION: A recent US Food and Drug Administration report highlighted concerns over nitrosamine (7-nitroso-3-(trifluoromethyl)-5,6,7,8-tetrahydro[1,2,4] triazolo-[4,3-a]pyrazine [NTTP]) impurities in sitagliptin, prompting investigations into its safety profile. The present study aimed to determine if the use of NTTP-contaminated sitagliptin, in comparison with other dipeptidyl peptidase-4 (DPP-4) inhibitors, is associated with an increased cancer risk. MATERIALS AND METHODS: This retrospective cohort study secondarily used the National Database of Health Insurance Claims and Specific Health Checkups of Japan, encompassing data on >120 million individuals. The study involved patients who initiated DPP-4 inhibitor therapy (sitagliptin or other DPP-4 inhibitors) and continued its exclusive use for 3 years. Sitagliptin users were compared with other DPP-4 inhibitor users for assessing the occurrence of cancers, as defined by diagnosis codes. Further analyses focused on specific types of cancer, using either diagnosis codes or a combination of diagnosis and procedure codes. We also carried out various sensitivity analyses, including those with different exposure periods. RESULTS: Sitagliptin users (149,120 patients, 388,356 person-years) experienced 9,643 cancer incidences (2,483.0/100,000 person-years) versus 12,621 incidences (2,504.4/100,000 person-years) among other DPP-4 inhibitor users (199,860 patients, 503,952 person-years), yielding a minimal difference (incidence rate ratio 0.99, 95% confidence interval 0.97-1.02). A multiple Cox proportional hazards model showed no significant association between sitagliptin use and overall cancer incidence (hazard ratio 1.01, 95% confidence interval 0.98-1.04). Findings were also consistent across cancer types and sensitivity analyses. CONCLUSIONS: We observed no evidence to suggest an increased cancer risk among patients prescribed NTTP-contaminated sitagliptin, although continued investigation is needed.