Aspirin use is associated with a reduced risk of cholangiocarcinoma: a systematic review and meta-analysis

BACKGROUND: Aspirin has been revealed to probably decrease the risk of cholangiocarcinoma (CCC), which, nevertheless, is of controversy. To this end, a systematic review and meta-analysis was performed to investigate the above-described association. METHODS: We thoroughly searched PubMed, EMBASE, and ISI Web of Science for relevant studies published prior to October 2017, followed by random-effects model for calculation of pooled ORs and corresponding 95% CIs. Additionally, subgroup and sensitivity analyses were carried out to confirm whether the outcomes were stable. RESULTS: Nine articles, consisting of 12,535 CCC patients and 92,97,450 healthy controls, were enrolled in this study. We demonstrated a significantly decreased risk of CCC in those using aspirin, with studies being heterogeneous (OR=0.69; CI=0.43–0.94; I2=97.4%). Moreover, this relationship was detected only in case-control studies (OR=0.65; 95% CI=0.38–0.93), rather than cohort studies (OR=0.94; 95% CI=0.70–1.27). Besides, in separated analysis of intrahepatic CCC and extrahepatic CCC, aspirin was more strongly correlated with a declined risk of intrahepatic CCC (OR=0.33, 95% CI=0.26–0.39; I2=93.6%) than the risk of extrahepatic CCC (OR=0.56, 95% CI=0.41–0.73; I2=0%). CONCLUSION: Collectively, the aspirin administration was correlated with a significant 31% decreased risk of CCC, particularly in the intrahepatic CCC.