PO-436 Dose-dependent relationship between metformin and the occurrence of colorectal cancer among taiwanese patients with type 2 diabetes

Abstract

IntroductionIncreasing evidence suggests that metformin may be beneficial in the primary prevention of colorectal cancer (CRC) and a dose–response relationship has been reported. However, a long-term epidemiologic observation between treatment period, cumulative dose, and intensity of metformin and CRC is rarely reported. The aim of this study isMaterial and methodsThe dataset used for this nationwide population-based study is a cohort of 1,000,000 subjects randomly sampled from individuals enrolled in the Taiwan National Health Insurance system. The subjects with newly diagnosed type 2 diabetes mellitus (DM) between 1997 and 2007 were enrolled. A statistical algorithm, including the demographic data, treatment period, cumulative dose and intensity of metformin use, was compared between patients developing CRC and those without CRC.Results and discussions47 597 subjects were included in this study. The mean follow-time was 7.17±3.21 years. After adjustment, the utilisation of metformin was an independent protecting factor of CRC development (p<0.001). Although the protecting ability of for CRC development reduced during long-term therapy, the risk of developing CRC decreased progressively with either the higher cumulative dose or the higher intensity of metformin use (both p<0.001).ConclusionThis study revealed that the use of metformin significantly decreased the risk of CRC development in a dose-dependent manner in patients with type 2 DM in Taiwanese population. However, a gradual decline in medication adherence may reduce the protecting ability of metformin for CRC development during long-term therapy.