Aspirin Use Linked to Decreased Risk of Bile Duct Cancer

Regular use of aspirin may reduce the risk of developing cholangiocarcinoma, according to the results of a new study published in Hepatology.

In this study, researchers showed that individuals who regularly took aspirin had a 2.7- to 3.6-fold reduction in the risk of developing cholangiocarcinoma compared with those who did not take aspirin regularly. The study also uncovered risk factors for cholangiocarcinoma, which included smoking, diabetes, hepatitis B virus infection, primary sclerosing cholangitis, biliary tract diseases, and cirrhosis.

The results of this study build on prior evidence that showed that aspirin may protect against gastrointestinal and other types of cancers.

“Chronic persistent inflammation is one of the key elements that promotes cancer of the bile ducts, and well-known risk factors for bile duct cancer have all been shown to increase the risk for bile duct cancer by inducing chronic inflammation of the ducts,” said study author Jonggi Choi, MD, of the division of gastroenterology and hepatology at the Mayo Clinic College of Medicine in Rochester, Minnesota, in a statement. “Aspirin is an anti-inflammatory agent and may reduce the risk of bile duct cancer by reducing inflammation through inhibition of the cyclooxygenase enzyme. Previous studies have shown that aspirin also blocks additional biological pathways that promote cancer development.”

Choi and colleagues analyzed 2,395 cases of cholangiocarcinoma seen at the Mayo Clinic between 2000 and 2014, as well as 4,769 controls matched for age, sex, race, and residence from the Mayo Clinic Biobank. The cancer cases consisted of three subtypes of cholangiocarcinoma: intrahepatic (1,169 cases), perihilar (995 cases), and distal (231 cases). These subtypes are thought to be distinct diseases, since the severity of the disease, its natural history, and treatment responses of patients vary among them.

Once-weekly aspirin usage was defined as regular usage; 24.7% of cholangiocarcinoma patients and 44.6% of controls were regular aspirin users.

There was a consistent, significant inverse association with aspirin use and each cholangiocarcinoma subtype. The individuals using aspirin regularly had a 65%, 66%, and 71% lower risk of developing intrahepatic, perihilar, and distal cholangiocarcinoma, respectively (adjusted odds ratios, 0.35, 0.34, and 0.29, respectively; P < .001 for all three).

The patients who developed cholangiocarcinoma were about 59% less likely to report the regular use of aspirin compared with control individuals (P < .001).

Exploring the other risk factors of cholangiocarcinoma, the researchers found that primary sclerosing cholangitis was the most significant, increasing the risk of bile duct cancer by 171.2-fold, followed by biliary tract diseases, which increased the risk by 12.1-fold.

The researchers noted that further research is necessary to understand whether aspirin may be a safe and cost-effective way to protect individuals at higher risk of developing bile duct cancer. “The next steps should include population-based studies examining the associations of aspirin use with risk of bile duct cancer, and also clinical trials, particularly in populations at high risk for bile duct cancer, to confirm the benefit of aspirin for bile duct cancer prevention,” concluded study author Lewis R. Roberts, MB, ChB, PhD, in a press release.