In a new study, researchers found aspirin is linked to a reduction in the risk of developing several cancers of the digestive tract, including pancreatic and liver cancers.
The study is the largest and most comprehensive analysis to date of the link between aspirin and digestive tract cancers.
It found reductions in the risk of these cancers of between 22% and 38%.
The research was conducted by a team at the Mario Negri Department of Oncology.
Aspirin has been linked to a reduction in the risk of bowel cancer for some time, and other, smaller analyses have found associations with cancers of the esophagus (the food pipe or gullet) and stomach.
This analysis looked at the evidence from 113 observational studies investigating cancers in the general population published up to 2019, of which 45 studies were on bowel cancer and included 156,000 cases.
In addition to bowel cancer, the cancers included those of the head and neck, esophagus, stomach, the part of the stomach that connects to the esophagus (gastric cardia), liver, gallbladder and bile ducts (hepato-biliary) and pancreas.
The researchers found that regular use of aspirin, defined as taking at least one or two tablets a week, was linked to a big reduction in the risk of developing all these cancers, apart from head and neck cancer.
Specifically, aspirin use was linked to 27% reduced risk of bowel cancer (45 studies), 33% reduced risk of oesophageal cancer (13 studies), 39% reduced risk of gastric cardia (ten studies), 36% reduced risk of stomach cancer (14 studies), 38% reduced risk of hepato-biliary cancers (five studies), and 22% reduced risk of pancreatic cancer (15 studies).
Ten studies of head and neck cancer did not show a big reduction in cancer risk.
The researchers also analyzed the effect of aspirin dose and duration on bowel cancer.
They looked at the low dose (100mg), regular (325mg) and high dose (500mg), combined with how many times a day, week or month it was taken.
They found that the risk of cancer was reduced with increased dose; an aspirin dose between 75 and 100mg a day was linked to 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 choice of dose should also take into consideration the potential risk of stomach bleeds, which increases with higher aspirin doses.
These findings suggest there’s a beneficial effect of aspirin in the prevention of bowel and other cancers of the digestive tract.
The results for bowel, oesophageal and pancreatic cancers are consistent with evidence from clinical trials on aspirin in the prevention of heart and blood vessel diseases.
For pancreatic cancer, they found that the risk of the disease declined by 25% after five years among people who took aspirin regularly compared to those who did not.
In addition to stomach bleeds, the side effects of aspirin include bleeding in other parts of the body and, occasionally, haemorrhages.
One author of the study is Dr. Cristina Bosetti (Ph.D.), head of the Unit of Cancer Epidemiology at the Mario Negri Department of Oncology, Milan (Italy).
The study is published in the leading cancer journal Annals of Oncology.
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