Risk of cancer: Reduction with increased dose

Our findings on bowel cancer support the concept that higher aspirin doses are associated with a larger reduction in risk of the disease. Cristina Bosetti

The researchers also analysed the effect of aspirin dose and duration on bowel cancer. They looked at low dose (100mg), regular (325mg) and high dose (500mg), combined with how many times a day, week or month it was taken.

Dr Bosetti said: “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.

“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.”

Prof Carlo La Vecchia said: “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.

“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.