Researchers in Britain say an aspirin a day taken over a 10 year period can reduce the risk of colon cancer by as much as 74 percent.
The new study by scientists at the Department of Clinical Neurology, University of Oxford, shows that a daily dose of 300 milligrams of Aspirin may be helpful for those at high risk for the disease.
Colorectal cancer, also called colon cancer or bowel cancer, includes cancerous growths in the colon, rectum and appendix and is the third most common form of cancer and the second leading cause of death among cancers in the western world.
Many colorectal cancers are thought to arise from adenomatous polyps in the colon, these mushroom-like growths are usually benign and take at least 10 years to develop into cancer.
As a rule the diagnosis of localized colon cancer is via a colonoscopy and therapy is usually surgery followed in many cases by chemotherapy.
For the study lead researcher Dr. Peter Rothwell, a professor of neurology and colleagues tracked patients from two large randomized trials of Aspirin from the late 1970s and early 1980s, the British Doctors' Aspirin Trial and the UK-TIA Aspirin Trial.
The researchers found that taking Aspirin reduced the incidence of colorectal cancer by 37 percent over the next 5 years, and 74 percent over 10 to 15 years.
However they do point out that the risks associated with taking such a large dose of Aspirin might not be worth it for most people.
They also advise those with an increased risk of colorectal cancer consult their doctor about whether the benefits of daily Aspirin are likely to outweigh the risks in their particular case.
Dr. Peter Rothwell says the benefits in individuals at low risk of colorectal cancer will in the main be small.
Currently as many as 50 million adults in the United States are thought to take daily Aspirin for long-term prevention against heart attack and stroke; doses range from 81 milligrams a day or 325 milligrams a day and what is considered an appropriate long-term daily dose remains a moot point.
Dr. Rothwell says daily doses as high as 300-milligram also offer potential dangers such as gastrointestinal bleeding.
Experts are generally in agreement that though individuals at high risk of developing colorectal cancer could benefit from taking daily Aspirin the side effects of Aspirin need to be taken into account before a blanket recommendation it can be issued.
Other proven methods for preventing colon cancer are advocated such as regular screening for the disease, keeping active, maintaining a normal body weight and reducing the amount of red meat consumed.
The lifetime risk of colon cancer is about 1 in 20 for men and 1 in 30 for women but this risk increases if a close relative has had the disease.
It is a disease of old age and generally occurs after the age of 50; it is very rare for colon cancer to appear in a person younger than 50.
Each year, around 35,000 men and women in the UK alone are diagnosed with bowel cancer, and more than 16,000 die from the disease.
The report is published in the May 12 issue of The Lancet.