The adjusted odds ratios (AORs) supported the researchers’ conclusion that aspirin users were protected against all 3 subtypes. The team found that patients with any one of the subtypes were almost 60% less likely than controls to be aspirin users. A statistically significant 3-fold reduction in risk for cholangiocarcinoma was associated with aspirin use. These aspirin-related risk reductions were consistent for all subtypes: 3.4-fold for dCCA, 2.9-fold for iCCA, and 2.9-fold for pCCA. Compared with nonusers, and broken down among the subtypes, the participants who were current aspirin users had a 71% lower risk of developing dCCA, a 66% lower risk of developing pCCA, and a 65% lower risk of developing iCCA.

Although no difference was seen between those who used aspirin daily and those aspirin users who did not use the drug daily, the protection afforded by aspirin did vary over time. The protective effect of aspirin was stronger among those using the drug for more than 3 years compared with those who had been using it for 3 years or less. Use of high-dose vs low-dose also produced a difference among aspirin users. However, no significant difference was noted between daily aspirin users when compared with nondaily aspirin users.

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The researchers found that different subtypes of cholangiocarcinoma were susceptible to different risk factors. The most common risk factor for cholangiocarcinoma was primary sclerosing cholangitis (PSC). Biliary tract diseases and non-PSC related cirrhosis were the next most significant risk factors, followed by hepatitis B, diabetes, and smoking.

The Mayo Clinic team is planning another study to validate aspirin for the prevention of cholangiocarcinoma. They plan to initiate a case-control trial comparing aspirin use among controls with PSC without CCA and patients with PSC and CCA.


1. Choi J, Ghoz HM, Peerphatdit T, et al. Risk factors for cholangiocarcinoma: aspirin-use and the risk of cholangiocarcinoma [published online April 26, 2016]. Hepatology. doi:10.1002/hep.28529.