News · April 21, 2015
PracticeUpdate Editorial Team
April 19, 2015—Philadelphia—When taken long-term, regular aspirin use was associated with a modestly reduced overall risk for cancer, which reduction was driven primarily by a lowered risk for colorectal cancers. This result of a prospective study was presented at the American Association of Cancer Research Annual Meeting 2015 in Philadelphia from April 18 – 22, 2015.
Yin Cao, ScD, MPH, of Harvard University, Boston, Massachusetts, explained that the group collected data on aspirin use, cancer diagnoses, and other risk factors from 82,600 women from the Nurses’ Health Study and 47,651 men from the Health Professionals Follow-Up Study. After 32 years of follow-up, 27,985 incident cancers were documented.
Study participants who reporter consuming two or more aspirin tablets per week had a 5% decreased risk for overall cancer. This decrease in risk was driven mainly by a 20% reduction in gastrointestinal cancers, including a 25% reduction in colorectal cancers and a 14% reduction in gastroesophageal cancers.
Long-term, regular aspirin use and increased doses of aspirin appeared to drive the reduced risk of cancer. Significant risk reduction was seen only after 16 years of aspirin use (P = 0.001) and was no longer evident within 4 years of discontinuing use. The association of aspirin use with cancer risk was similar for women and men and did not vary by race, history of diabetes, family history of cancer, body mass index, smoking history, regular use of nonsteroidal anti-inflammatory drugs, or multivitamin use. No association was found between regular aspirin use and a decreased risk for non-gastrointestinal cancers, specifically, breast, lung, or prostate cancers.
“Previous studies of aspirin and cancer have been limited in terms of size, length of follow-up, and the ability to examine aspirin use in the context of other lifestyle factors,” said Dr. Cao. “Our research provides critical information regarding the full constellation of potential benefits of aspirin use, at a range of doses, timing, and duration of use, within a large population of individuals.”
Senior study author Andrew T. Chan, MD, MPH, also of Harvard University, said, “Aspirin has been shown to be effective in the prevention of heart attacks and strokes, particularly among individuals who have had a prior history of these cardiovascular events. Recent findings, however, suggest that such benefits may not be as pronounced for individuals at low risk for heart attacks and strokes.”
Dr. Chan added, “Our findings suggest that for many individuals the potential benefits of aspirin for the prevention of cancer may merit greater consideration than prevention of cardiovascular events. Our findings strengthen the case for further research into defining subsets of the population who may obtain preferential benefit from regular aspirin use.” Dr. Chan cited an example of this strategy. “We recently showed that an individual’s genetic background might influence the apparent reduction in risk of colorectal cancer associated with aspirin use.”
Dr. Cao cautioned that despite the results, it is premature to recommend general use of aspirin for cancer prevention. “Individuals, in consultation with their physicians, need to consider the potential risks of taking aspirin, including gastrointestinal bleeding,” he said. “The results of ongoing research to develop more tailored treatment based on a personalized assessment of risks and benefits will be critical before recommending aspirin for chemoprevention of cancer.”