People taking 75-150 mg of aspirin continuously for 5 years or longer saw an associated 27% reduced risk for colorectal cancer.
CRC is the second leading cause of cancer death. About 9 out of 10 people diagnosed with CRC are at least 50 years old.
Forty percent of Americans aged 50 years and over have benign tumors in the colon; it is estimated that 2% will progress to cancer. As this form of cancer is especially slow to develop, it is open to successful preventive actions such as taking low-dose aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs).
A team from the Department of Clinical Epidemiology at Aarhus University Hospital in Denmark found that people taking 75-150 mg of aspirin continuously for 5 years or longer saw an associated 27% reduced risk for CRC, increasing to 30-45% for those taking non-aspirin NSAIDs. The largest risk reductions come from NSAIDs that target specific enzymes for inflammation and pain.
The study group was made up of 10,280 adults with first-time CRC and 102,800 control participants. Lifestyle factors such as diet, weight and exercise were not measured.
Asked if this effect would apply to a general population or a specific one presenting with specific symptoms, study author Søren Friis - senior scientist associate professor in the Department of Clinical Epidemiology - told Medical News Today:
"It is important to evaluate the association between aspirin or other NSAIDs in the general population, as well as within selected study populations of high-risk individuals with colorectal cancer, including persons with familial/hereditary disposition, previous history of colorectal adenomas or cancer or obesity, while balancing the chemopreventive effects against the potential harms."
Additional research warranted to determine optimal aspirin use
"Some studies indicate that the preventive effect of aspirin against colorectal cancer is largest among overweight/obese persons," Friis told us. "There is a need for studies that examine the benefit/risk profile in various populations, that is, balance the chemopreventive effects of aspirin and other NSAIDs against potential harms, including gastrointestinal bleeding, stroke, and - for non-aspirin NSAIDs - cardiovascular adverse events."
The authors of the study say further research is required to determine the optimal use of aspirin for cancer prevention.
"Additional research is needed to identify individuals for whom the risk-benefit profile is in favor of chemopreventive therapy with aspirin, and to examine effect modification according to factors such as age and weight," Friis told MNT. "We have plans to examine the influence of lifestyle factors and obesity on the effect of aspirin/NSAIDs against colorectal and prostate cancer using a prescription registry for diet, cancer, and health."
A "prescription registry", as available in Denmark, provides practitioners with direct, secure access to continuous and complete information on prescription histories.
"A further advantage with this approach," added Friis, "is the ability to combine prescription data with information on over-the-counter use of notably high-dose aspirin."
This is not the first study to link aspirin use to reduced cancer risk. Earlier this month, MNT reported on a study associating regular aspirin use with lower risk of specific cancers in overweight individuals, particularly womb and colon cancers.