Statins associate with lower risk of biliary tract cancers: A systematic review and meta‐analysis

BACKGROUND: Biliary tract cancers (BTCs), encompassing cholangiocarcinoma (CCA), gallbladder (GBC), and ampulla of Vater cancers (AVC), are common hepatobiliary cancer after hepatocellular carcinoma with a high mortality rate. As there is no effective chemopreventive agent to prevent BTCs, this study aimed to explore the role of statins on the risk of BTCs. METHODS: PubMed, Embase, and Cochrane Library from inception until 24 April 2020 were searched according to the Meta‐Analyses of Observational Studies in Epidemiology (MOOSE) guidelines. The adjusted risk ratios (aRRs) of BTCs and individual cancer were pooled using a random‐effects model. RESULTS: Eight observational studies (3 cohort and 5 case–control studies) were included with 10,485,231 patients. The median age was 68.0 years (IQR: 67.0–71.5) and 48.3% were male. Statins were associated with a lower risk of all BTCs (aRR: 0.67; 95% CI: 0.51–0.87). The pooled aRR for CCA was 0.60 (95% CI: 0.38–0.94) and GBC was 0.78 (95% CI: 0.68–0.90). There was only one study on AVC with aRR of 0.96 (95% CI: 0.66–1.41). The pooled aRR for lipophilic and hydrophilic statins was 0.78 (95% CI: 0.69–0.88) and 0.70 (95% CI: 0.61–0.80), respectively. The effects were attenuated in studies that adjusted for aspirin and/or non‐steroidal anti‐inflammatory drugs (aRR: 0.80, 95% CI: 0.72–0.89) and metformin (aRR: 0.80, 95% CI: 0.72–0.90). CONCLUSIONS: Statins, both lipophilic and hydrophobic, were associated with a lower risk of BTCs, particularly CCA and GBC.