Cholelithiasis and risk of pancreatic cancer: systematic review and meta-analysis of 21 observational studies

To investigate the association between cholelithiasis and risk of pancreatic cancer (PaC). We identified eligible studies in MEDLINE and EMBASE up to August 1, 2013 and the reference lists of original studies and review articles on this topic. Summary relative risks (SRRs) with their 95 % confidence intervals (CIs) were calculated with a random-effects model. Twenty-one studies (15 case-control studies, 6 cohort studies) met eligibility criteria. The current data suggest that cholelithiasis is associated with a 25 % excess risk of PaC (SRRs = 1.25, 95 % CI 1.10-1.41; test for heterogeneity p = 0.006, I (2) = 47.6 %). In subgroup analysis of timing of exposure, seven of eight studies in patients whose diagnosis of cholelithiasis made more than specified year (5, 3, 2, or 1 year) prior to cancer diagnosis showed no association for PaC, while all three studies in patients diagnosed less than specified year before cancer diagnosis showed a positive association. There was no publication bias in the present meta-analysis. This meta-analysis supports the hypothesis that a history of cholelithiasis may significantly increase PaC risk, particularly in Asian countries. However, the positive association disappeared over time, suggesting that cholelithiasis may be the early symptoms of PaC.