Aspirin may lower the risk of deadly cancers of the digestive tract, such as pancreatic and liver cancer. In the largest and most comprehensive study of its kind, researchers found that aspirin was associated with a reduced risk of developing digestive tract cancers by between 22 and 38 percent.
Previous studies have established a link between aspirin and a lower risk of bowel, esophagus, and stomach cancers.
The current research, which is published by the European Society for Medical Oncology, analyzed the results of 113 observational studies. The study was focused on cancers of the bowel, head and neck, esophagus, stomach, liver, gallbladder and bile ducts, and pancreas.
The researchers found evidence to suggest that taking at least one or two aspirin a week significantly lowers the risk of developing all of the cancers examined in the study, with the exception of head and neck cancer.
Aspirin was linked to a 27-percent reduced risk of bowel cancer.
“There are about 175,000 deaths from bowel cancer predicted for 2020 in the EU, of which about 100,000 will be in people aged between 50 and 74,” said study senior author Professor Carlo La Vecchia.
“If we assume that regular use of aspirin increases from 25% to 50% in this age group, this would mean that between 5,000 to 7,000 deaths from bowel cancer and between 12,000 and 18,000 new cases could be avoided if further studies show that aspirin does indeed cause the reduction in cancer risk.”
“Corresponding figures would be approximately 3,000 deaths each for esophageal, stomach and pancreatic cancer, and 2,000 deaths from cancer of the liver. Given the unfavorable prognosis for these cancers, the number of new cases would be only slightly greater.”
The team analyzed the effect of aspirin dose and duration on bowel cancer, combining data for how frequently aspirin was taken at low, regular, or high doses.
Study lead author Dr. Cristina Bosetti is the head of the Unit of Cancer Epidemiology at the Mario Negri Department of Oncology in Milan.
“We found that the risk of cancer was reduced with increased dose; an aspirin dose between 75 and 100mg a day was associated with a 10% reduction in a person’s risk of developing cancer compared to people not taking aspirin; a dose of 325mg a day was associated with a 35% reduction, and a dose of 500mg a day was associated with a 50% reduction in risk. However, the estimate for high dose aspirin was based on just a few studies and should be interpreted cautiously,” explained Dr. Bosetti.
“Our findings on bowel cancer support the concept that higher aspirin doses are associated with a larger reduction in risk of the disease. However, the choice of dose should also take into consideration the potential risk of stomach bleeds, which increases with higher aspirin doses.”
“Compared to people who did not take aspirin regularly, the risk of bowel cancer declined in regular aspirin users up to ten years. The risk was reduced by 4% after one year, 11% after three years, 19% after five years and 29% after ten years.”
Professor La Vecchia said the findings suggest there is a beneficial effect of aspirin in the prevention of bowel and other cancers of the digestive tract.
“The results for bowel, esophageal, and pancreatic cancers are consistent with evidence from clinical trials on aspirin in the prevention of heart and blood vessel diseases.”
“The findings for pancreatic and other digestive tract cancers may have implications for the prevention of these highly lethal diseases. For pancreatic cancer, we found that risk of the disease declined by 25% after five years among people who took aspirin regularly compared to those who did not.
“Taking aspirin for the prevention of bowel cancer, or any other cancers, should only be done in consultation with a doctor, who can take account of the person’s individual risk. This includes factors such as sex, age, a family history of a first-degree relative with the disease, and other risk factors. People who are at high risk of the disease are most likely to gain the greatest benefits from aspirin,” said Professor La Vecchia.
The side effects of aspirin include stomach bleeds, bleeding in other parts of the body, and hemorrhages. The study is limited in that it is based on observational studies and can only show that aspirin is associated with a reduced risk of digestive tract cancers.
The research is published in the Annals of Oncology.