A new study provides further evidence of the anticancer properties of aspirin, after finding the drug may be effective for reducing the development of bile duct cancer.
Bile duct cancer, also known as cholangiocarcinoma, is a cancer that begins in the bile ducts.
Bile ducts are thin tubes that remove bile - a yellow-green fluid - from the liver and gallbladder and transport it to the small intestine, where it helps with digestion.
There are three types of bile duct cancers: intrahepatic, perihilar, and distal. Perihilar bile duct cancer begins in the hilum - where the left and right hepatic bile ducts join - while distal bile duct cancer develops further down the small intestine.
According to the American Cancer Society, bile duct cancer is uncommon relative to other cancers, affecting around 2,000-3,000 people in the United States every year.
However, survival rates for bile duct cancer are low; the 5-year relative survival rate for people diagnosed with intrahepatic bile duct cancer is only 15 percent, while the 5-year survival rate stands at 30 percent for those diagnosed with perihilar or distal bile duct cancers.
Now, new research - recently published in the journal Hepatology - suggests aspirin use may reduce the likelihood of developing bile duct cancer.
Aspirin users up to 3.6 times lower risk for bile duct cancer
To reach their findings, co-lead author Dr. Jonggi Choi and colleagues, from the Mayo Clinic College of Medicine in Rochester, MN, assessed the aspirin use of 2,395 individuals with bile duct cancer who visited the Mayo Clinic between 2000-2014.
The data were compared with 4,769 healthy controls who were matched for age, sex, race, and residence.
Aspirin was used by 591 (24.7 percent) patients with bile duct cancer and 2,129 (44.6 percent) healthy controls.
Compared with individuals who did not use aspirin, those who did use aspirin were 2.7-3.6 times less likely to develop bile duct cancer, the researchers report.
Additionally, on analyzing the results by the three bile duct cancer subtypes, the team found that the risk of each subtype varied with certain factors. These factors included primary sclerosing cholangitis - inflammation and scarring of the bile ducts - cirrhosis, hepatitis B, diabetes, and smoking.
"This supports the hypothesis that the three CCA [cholangiocarcinoma] subtypes are distinct diseases and that each subtype thus has its own susceptibility to risk factors," say the authors.
Aspirin may target pro-inflammatory enzyme to prevent bile duct cancer
While the researchers are unable to explain exactly how aspirin may protect against bile duct cancer, they suggest it may be down the anti-inflammatory properties of the drug.
"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," explains Dr. Choi.
"Aspirin is an anti-inflammatory agent and may reduce the risk of bile duct cancer by reducing inflammation through inhibition of the cyclooxygenase enzyme," he adds. "Previous studies have shown that aspirin also blocks additional biological pathways that promote cancer development."
The researchers believe their findings suggest aspirin use could be a viable strategy to lower the risk of bile duct cancer.
"Until now, there has been little evidence of a potential role for aspirin in the prevention of bile duct cancer. Our study provides the first evidence for this."
Dr. Roongruedee Chaiteerakij, co-lead study author
However, the authors say further research is needed to determine whether the drug is safe and cost-effective for this purpose.
"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," says co-lead study author Lewis Roberts.