SAN FRANCISCO, CA—Use of aspirin significantly reduced the risk of three subtypes of cholangiocarcinoma, data presented at The Liver Meeting® 2015 have shown.

Cholangiocarcinoma, the second most common primary liver cancer, is classified by anatomic location as intrahepatic, perihilar, and distal, explained Jonggi Choi, from the Mayo Clinic College of Medicine, Rochester, MN.

Dr. Choi and colleagues evaluated 2,395 cases of cholangiocarcinoma seen at Mayo Clinic between 2000 and 2014 to determine the associations between aspirin use and risk factors for each cholangiocarcinoma subtype individually. Of the total cholangiocarcinoma cases, 1,169 were intrahepatic, 995 perihilar, and 231 distal.  Relationships between aspirin use and other risk factors were calculated using logistic regression analysis.

There were 591 cholangiocarcinoma cases selected and 2,129 matched controls who took aspirin. Of the total aspirin users, 78.5% of cases and 44.6% of controls were current users (P<0.001).

Current use of aspirin was inversely linked to risk of cholangiocarcinoma, with an adjusted odds ratio (AOR) of 0.34 (95% CI: 0.30–0.39; P<0.001); the lowest inverse risk was observed for aspirin use for more than 3 years; AOR 0.12 (95% CI: 0.10–0.15; P<0.001).

On multivariate analysis, risk factors associated with cholangiocarcinoma included primary sclerosing cholangiitis (PSC; P<0.001), biliary tract disease (P<0.001), non-PSC related cirrhosis (P<0.001), diabetes (P<0.001), hepatitis B virus infection (P=0.042), and smoking/ever-smoker (P<0.001). Non-PSC related cirrhosis was linked to both intrahepatic and perihilar cholangiocarcinoma but not with distal cholangiocarcinoma.

Study authors noted that isolated inflammatory bowel disease without PSC was not related to cholangiocarcinoma (all three subtypes combined (P<0.081); in addition, no association was found for hepatitis C virus infection obesity (P=0.069) or nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (P=0.526).

Overall, “aspirin use was significantly associated with an approximately three-fold reduction in  cholangiocarcinoma risk,” they noted. “Risk reductions by aspirin use were consistent across all three subtypes; ie, 2.9-fold for intrahepatic, 2.9-fold for perihilar, and 3.4-fold for distal.” 

“This study is the first comprehensive report of risk factors for all the three cholangiocarcinoma subtypes,” the study authors concluded. “We were therefore able to show that each risk factor contributes” to the development of each subtype “in different magnitudes.”