Does Aspirin Reduce Your Risk of Colon Cancer?

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There has been a growing body of evidence suggesting that regular use of aspirin may lower the risk of certain cancers, particularly those of the gastrointestinal (GI) tract. This gradual upsurge in interest has been countered, however, by the well-known risks associated with aspirin—notably peptic ulcer disease, intestinal bleeding, and less commonly hemorrhagic stroke.

It’s time to take a hard look at all the data and truly assess the benefits and risks. According to investigators reporting in the Annals of Oncology, here’s what we know so far.

Aspirin and Colon Cancer

Regular, long-term use of aspirin substantially reduces the risk of developing colorectal cancer in persons aged 50 to 65. Long-term use was necessary to see the effect, which appeared only after three years. For persons at average risk of developing colon cancer (those without a family history), researchers estimate that 10 years of aspirin use would reduce the risk by 7 percent in women and 9 percent in men.

It’s important to remember, however, that these are relative risks—the vast majority of people will not develop colorectal cancer whether or not they take aspirin (on average, about 137,000 persons are diagnosed with colorectal cancer each year in the US). The benefit was seen with low dose, “baby” aspirin (75 or 81 mg), while higher doses were not found to confer added protection.

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The Risks

Bleeding remains an important potential hazard of aspirin use, but serious bleeds are uncommon. From a baseline rate of 0.03 to 0.06 percent (3 to 6 people out of 10,000) of persons who suffer from hemorrhagic strokes per year, aspirin raises that risk by about one-third—still very low. Similarly, from a baseline rate of 0.7 per 1,000 persons who suffer from gastrointestinal bleeds, the increase in incidence of bleeding ranges from 30 to 70 percent.

The risk of a serious bleed is higher in older patients, men, diabetics, hypertensives, and those who are overweight, smoke, or consume excess alcohol. Infection with the bacteria Helicobacter pylori, which inhabits and damages the gastrointestinal tract, also raises the risk of bleeding, but investigators remain unsure of the benefits of screening for H. pylori prior to initiating aspirin therapy.

Aspirin’s Effect on Other Cancers

A smaller benefit was seen in other cancers (especially other GI cancers such as the far less common malignancies of the stomach and esophagus) and—to an even lesser extent—in reducing overall heart attacks and stroke as well. Most strokes are not hemorrhagic, but ischemic—caused by the same hardening of the arteries that leads to heart attacks.

These findings have attracted a lot of attention in the medical community. If you are between the ages of 50 and 65 and are interested in seeing if aspirin prophylaxis is right for you, talk to your primary health care provider who will assess the potential benefits and risks and help you decide on the best course of action.


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