Daily Aspirin Reduces Colorectal Cancer, Perhaps Others
Professor Peter Rothwell practices what he preaches: several years ago he and his wife began taking low-dose aspirin to reduce the risk of cancer. Rothwell has also authored a study in which he found that taking a daily low-dose of aspirin for about five years cut the chance of developing colorectal cancer by 24 percent, and suggests it may reduce the risk for other cancers as well.
Low-dose of aspirin may reduce hard-to-detect colorectal cancer
Daily use of aspirin is commonly associated with helping to reduce the risk of cardiovascular events, such as heart attack and stroke. Rothwell, who is a professor of neurology at John Radcliffe Hospital and the University of Oxford in the United Kingdom, believes that “it is likely that in five years people will be taking it to prevent non-vascular diseases like cancer as well.”
Rothwell and his research team evaluated data from four randomized trials that included more than 14,000 people who had received aspirin (75 mg) or placebo for an average of six years. After reviewing data from an average of 18 years of follow-up, the team determined that use of low-dose aspirin reduced the 20-year risk of developing colorectal cancer by 24 percent and the risk of dying from the cancer by 35 percent.
Daily aspirin did not reduce the risk of cancer equally throughout the colon, however. The investigators found that 70 percent of the reduced risk was associated with fewer cancers in the right section of the colon (proximal colon), and that aspirin did not seem to have a positive impact on the lower part of the colon (distal colon) and little effect on rectal cancer.
This finding is good news, because cancers of the proximal colon are not effectively prevented by screening using sigmoidoscopy or colonoscopy. The risk of internal bleeding of the stomach lining associated with aspirin use is reduced at lower doses like the one evaluated in this study.
The National Cancer Institute reports that an estimated 102,900 new cases of colon cancer and 39,670 new cases of rectal cancer will be diagnosed in the United States in 2010, with approximately 51,370 deaths from colorectal cancer predicted.
In the United States, colorectal cancer is the fourth most common cancer in men, after skin, prostate, and lung cancer, and the fourth most common cancer in women, after skin, breast, and lung cancer. In Britain, colorectal cancer is diagnosed in about 39,000 people each year and is the third most common cancer. Worldwide, about 1 million new cases of colorectal cancer are diagnosed each year.
Other experts commented in an editorial that accompanied the study, which appears in The Lancet. Drs. Robert Benamouzig and Bernard Uzzan of the Avicenne Hospital in Bobigny, France, wrote that “this interesting study could incite clinicians to turn to primary prevention of colorectal cancer by aspirin at least in high risk populations. Specific guidelines for aspirin chemoprevention would be the next logical step.”
Rothwell notes that in addition to colorectal cancer, other types of cancer will also respond to this low-dose aspirin therapy because the drug blocks the effects of cyclo-oxygenase, which is produced by some forms of cancer. Before anyone begins taking aspirin, however, they should consult their healthcare provider.
National Cancer Institute
Rothwell PM et al. The Lancet 2010 Oct 22; DOI: 10.1016/S0140-6736(10)61543-7