Taking aspirin linked to lower risk of colorectal cancer; Men and Women Awareness

    Aspirin has many uses, from easing a headache or cooling a fever to preventing heart attacks and the most common kind of stroke. It may be time to add “preventing colorectal cancer” to the list.

New results from the Women’s Health Study, a clinical trial that evaluated the benefits and risks of low-dose aspirin and vitamin E among nearly 40,000 women, show that aspirin reduces the risk of developing colorectal cancer by 20%. The effect isn’t immediate, but instead takes ten to 20 years to be seen. 

Several earlier studies have linked aspirin use to protection against colorectal cancer. But they were observational studies, which can’t prove cause and effect. The Women’s Health Study was a randomized trial, the gold standard of medical research. As part of the trial, half of the women took 100 milligrams of aspirin every other day and the other half took a placebo every other day. Neither the women, their doctors, nor the researchers knew who was taking what.

The trial began in 1993 and ended in 2004. The initial results showed that aspirin reduced the risk of stroke and also reduced the risk of heart attack among women over age 65, while vitamin E had no effect on heart attack, stroke, or cancer.

After the study ended, the researchers continued to follow more than 33,000 women through March 2012. These women were asked to continue the regimen, although the researchers no longer provided the pills. It was among this group that the researchers saw a 20% lower rate of colorectal cancer.

Interestingly, the researchers saw no difference in colorectal polyps between groups. Polyps are small growths in the wall of the colon or rectum. Some are harmless, some progress to cancer. The new results suggest that aspirin doesn’t prevent polyps from forming, but instead may prevent them from becoming cancerous.

Aspirin isn’t without its drawbacks, including gastrointestinal bleeding and ulcer formation. Both occurred slightly more often among women taking aspirin:

• gastrointestinal bleeding: 8.3% in the aspirin group, 7.3% in the placebo group
• ulcer formation: 7.3%in the aspirin group, 6.2% in the placebo group.

Although this study included only women, the results probably apply to men, too. Other studies demonstrating a connection between taking aspirin and protection against colorectal cancer have mainly included men