Cancer - Prostate(구연) (E-104) The effect of metformin use and the incidence of prostate cancer in type 2 diabetes mellitus patients: A nationwide population-based study 충북대학교 의과대학 비뇨의학교실 Ho Won Kang, Kyeong Kim, Hee Youn Lee, Sung Pil Seo, Won Tae Kim, Yong-June Kim, Seok-Joong Yun, Sang-Cheol Lee, Wun-Jae Kim PURPOSE: Metformin has been known to have an antitumor effect in various cancers. However, the effect in prostate cancer (PCa) are controversial. The current study investigated the effect of metformin on the incidence of PCa. MATERIALS AND METHODS: The database was provided by the National Health Insurance Service of the Republic of Korea. A cohort of patients with newly diagnosed type 2 diabetes mellitus (DM) in 2007 was identified. To remove the insulin bias, cohort was divided into regular insulin users and insulin nonusers group. RESULTS: A total of 171,709 patients were newly diagnosis in 2007 in Korea. Among them, 75,624 regular DM drug users were finally enrolled for the study. Patients who had claimed for anti-diabetic drugs less than 6 months or irregular drug users were excluded (Figure 1 and Table 1). In insulin nonuser group, the cumulative PCa incidence rate in metformin users was not statistically different from that of metformin nonusers (P= 0.28, by the Wilcoxon test) (Figure 2). Relative risk of PCa development among metformin users was not significant in the insulin nonuser group. Thiazolidinedione, sulfonylurea, regular metformin, and duration of metformin did not affect the difference of PCa incidence (Table 2). CONCLUSIONS: Metformin use could not decrease the incidence of PCa in type 2 DM patients. keywords : Prostate cancer, Metformin, Diabetes