Diabetes mellitus and increased risk of extrahepatic cholangiocarcinoma: a meta-analysis.

ABSTRACT

BACKGROUND/AIMS: Diabetes mellitus (DM) has been considered to be relevant to an increased risk of several different types of cancers. However, its relationship with extrahepatic cholangiocarcinoma (ECC) remains unclear. METHODOLOGY: To investigate a quantitative assessment of this relationship, we performed a meta-analysis to evaluate the association between diabetes and the risk of ECC. We identified studies by searching Embase (from 1 January 1974 to 30 June 2012), Medline (from 1 January 1966 to 30 June 2012), and the reference lists of related articles. Summary relative risks (RRs) with corresponding 95% CIs were calculated with a random-effects model. RESULTS: A total of 9 articles (4 case-control and 5 cohort studies) were included in this study. Compared with those without DM, individuals with DM had an increased risk of ECC (for case-control studies summary OR=1.61, 95% CI 1.05-2.49, p=0.063 for heterogeneity; for cohort studies summary RR=1.61, 95% CI 1.14-2.29, p=0.005 for heterogeneity). The funnel plot showed no evidence for publication bias concerning DM and the risk of ECC (Egger's test, p=0.699; Begg's test, p=0.175). CONCLUSIONS: These findings strongly reveal the positive link between DM and the increased risk of ECC.