Aspirin has long been known to have cancer prevention effects, but it has not been widely used for this because of concerns about potential harm. Experts have now declared, for the first time, that the benefits of taking aspirin to prevent some types of cancer outweigh the harms.
This conclusion comes from a review published online August 6 in the Annals of Oncology.
"Whilst there are some serious side effects that can't be ignored, taking aspirin daily looks to be the most important thing we can do to reduce cancer after stopping smoking and reducing obesity, and will probably be much easier to implement," first author Jack Cuzick, PhD, head of the Centre for Cancer Prevention at Queen Mary's University of London in the United Kingdom, in a press release.
"Our study shows that if everyone aged between 50 and 65 started taking aspirin daily for at least 10 years, there would be a 9% reduction in the number of cancers, strokes, and heart attacks overall in men, and around 7% in women," Dr. Cuzick continued. "The total number of deaths from any cause would also be lower, by about 4% over a 20-year period. The benefits of aspirin use would be most visible in the reduction in deaths due to cancer."
The review is the first to provide such strong support for evidence about the benefits of taking aspirin in cancer prevention.
"It has long been known that aspirin — one of the cheapest and most common drugs on the market — can protect against certain types of cancer. But until our study, where we analyzed all the available evidence, it was unclear whether the pros of taking aspirin outweighed the cons," Dr. Cuzick said.
However, the authors stop short of recommending the daily use of aspirin.
Consensus of the Best Minds
"In the scientific world, this is an important paper. It represents a confirmation of the emerging consensus by some of the best minds in this field who have looked at these data for years," Leonard Lichtenfeld, MD, deputy medical director of the American Cancer Society, told Medscape Medical News.
Should doctors routinely recommend aspirin for patients 50 to 65 years of age?
"The authors fall short of making an absolute recommendation about this," Dr. Lichtenfeld noted. However, "the evidence is clearly strong that low-dose aspirin has been demonstrated to significantly reduce incidence and deaths from certain GI cancers," particularly colorectal cancer.
An answer could come from the US Preventive Services Task Force, which has begun a comprehensive review of the role of aspirin for cancer prevention, according to Dr. Lichtenfeld.
"If the task force says people should be taking aspirin routinely, that's a very strong recommendation," he said. "That might be a game changer, but we don't know yet."
"Patients will need to make individual decisions about how much risk they are willing to accept to prevent cancer," he explained. A person with a family history of colorectal cancer might be more willing to accept risk than a person with no such history. "That's what informed decision making is all about."
Review of Recent Evidence
Recent research has indicated that aspirin could decrease overall mortality by decreasing deaths from cancer, rather than from cardiovascular disease. In fact, advances in the treatment of cardiovascular disease might have eclipsed the benefits of aspirin.
One study suggested that taking aspirin daily for about 5 years could decrease digestive cancers by 40%, which would lead to a 16% reduction in the rate of overall cancer mortality (J Natl Cancer Inst. 2012;104:1208-1217). When that study was published, experts did not recommend aspirin for cancer prevention because of the risk for serious gastrointestinal bleeding, stomach ulcers, and stroke.
In their review, Dr. Cuzick and colleagues examined data from recent systematic reviews and individual studies on the effect of aspirin on major digestive tract cancers, and on cancers of the breast, prostate, and lung.
Results suggest that over 10 years, about 33 to 127 people would need to take aspirin to prevent 1 major event, and 46 to 213 people would need to take aspirin to prevent 1 death. Reductions in cancer would account for 61% to 80% of the benefit of aspirin use, and 30% to 60% of this would come from reductions in colorectal cancer.
The evidence for the reduction in incidence and death from colorectal cancer with aspirin use is "overwhelming", according to Dr. Cuzick and colleagues.
They found a 30% to 35% decreased risk of developing colorectal cancer with aspirin use, and a 35% to 40% decreased risk of dying from this cancer. They also found a 25% to 30% decreased risk of developing and a 45% to 50% decreased risk of dying from esophageal cancer, and a 25% to 30% decreased risk of developing and a 35% to 40% decreased risk of dying from stomach cancer. Smaller effects were found for breast, prostate, and lung cancer.
The benefits of taking aspirin appeared around 3 years after starting use. Death rates started to decrease after 5 years, and daily doses from 75 to 100 mg were linked to beneficial effects.
The most serious harm with aspirin use was stroke, which was rare but was linked to a 21% increased risk for mortality. Bleeding outside the brain was more common. Chronic aspirin use was linked to a 60% to 70% increase in the risk of dying from digestive tract bleeding. The rates of developing and dying from digestive tract complications were low for those younger than 70 years, but increased "steeply" for those older than 70.
This study was partially sponsored by the American Cancer Society. Dr. Cuzick reports being on the advisory board of Bayer. Several of his coauthors report financial relationships with pharmaceutical companies, as detailed in the publication. Dr. Lichtenfeld has disclosed no relevant financial relationships.
Ann Oncol. Published online August 6, 2014. Abstract
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Cite this: Aspirin Daily to Keep Cancer Away: Benefits Outweigh Harms - Medscape - Aug 06, 2014.