Low-Dose Aspirin May Decrease Risk of Colorectal Cancer

Health experts can't seem to make up their minds about aspirin. Some believe this oral medication that's used to treat common aches and pains has the power to reduce your cancer risk. Yet studies involving the drug also show that it can raise the risk of gastrointestinal bleeding-a problem particularly difficult for those with colon and stomach cancers.

A study led by Nancy Cook, Associate Biostatistician at Brigham and Women's Hospital, and Professor of Medicine at Harvard Medical School in Boston, took a look at the long-term benefits of regular low-dose aspirin intake concering reduced cancer risk. 

Over 20 years, since an Australian study first suggested that aspirin may have anti-cancer properties, researchers found that the headache drug may prevent and treat different types of cancer, including colorectal. Some studies even suggest that colon cancer survival improves with aspirin use.

However, most studies haven't examined the long-term benefits of the drug. To do this, Cook and colleagues studied the data of 39,876 women aged 45 and over who took part in the Women's Health Study (WHS), run by Brigham and Women's Hospital and Harvard Medical School.

The WHS looked at the benefits and risks of low-dose aspirin and vitamin E in the prevention of heart disease and cancer. 

The WHS participants were enrolled between 1994 and 1996 and randomly assigned to one of two groups. One group took 100 mg of aspirin every other day and the other group took placebo.

Every year following enrollment, until the end of the trial in March 2004, the women received a 12 month's supply of aspirin or a placebo. And every 6 to 12 months, they also filled in questionnaires that asked them about how well they were adhering to the dosing schedule, were there any adverse effects, were they taking aspirin over and above the dose for the study and other information that might affect the results such as additional risk factors.

At the end of the trial, results showed that aspirin had no effect on the risk of developing lung or breast cancer. However, it did show a reduced risk of colorectal cancer, but did not emerge until well into the post-trial follow up, 10 years after use. Long term use of low-dose aspirin, as stated before, was also linked to more gastrointestinal bleeding and peptic ulcers.

Researchers believe weighing the pros and cons of taking aspirin long-term for patients with colorectal cancer will be a deciding factor if the drug should be taken for certain patients.

More information regarding the study can be found in the journal the Annals of Internal Medicine.