"It's exciting that an inexpensive, commonly used medication may be of benefit among this group of patients who are worried about having their cancer recur," said Dr. Andrew Chan. (M. Spencer Green/AP Photo)

Some people diagnosed with colon cancer who take Aspirin may reduce their risk of dying from the disease by nearly 30 per cent compared with those who don't take the pills, a new study suggests.

Acetylsalicylic acid (ASA) was developed as a painkiller and marketed as a headache medication or to treat aches and pains. Research has also suggested its regular use may help to prevent colorectal cancer in people at high risk of the disease.

In Wednesday's issue of the Journal of the American Medical Association, Dr. Andrew Chan of Harvard Medical School in Boston and his colleagues reported patients who already have colon cancer may benefit from taking Aspirin along with surgery and chemotherapy.

"It's exciting that an inexpensive, commonly used medication may be of benefit among this group of patients who are worried about having their cancer recur," Chan said.

Tumour typing

But ASA didn't work for everyone, he noted. It was most effective in patients with the most common type of tumour which overproduces the COX-2 enzyme.

The finding makes sense, the researchers said, since Aspirin blocks the effects of the enzyme, which is thought to contribute to the progression and spread of tumours.

In the observational study, Chan and his colleagues analyzed data from two large, ongoing studies of health professionals. Researchers tracked 1, 279 men and women with nonmetastatic colorectal cancer who were followed for an average of 12 years.

Among the 549 participants who used Aspirin regularly after their cancer diagnosis, 81 died from colorectal cancer, or about 15 per cent. In comparison, among the 730 people who didn't use Aspirin, 141 died of the disease, or about 19 per cent.

The 29 per cent relative reduction in risk of cancer death was found after taking other cancer risk factors into account, such as family history. The team also found a 21 per cent lower risk for overall mortality among those taking the drug.

ASA seemed to help those stage I, II and III of the disease.

"These results suggest that Aspirin may influence the biology of established colorectal tumors in addition to preventing their occurrence," the study's authors wrote.

"Our data also highlight the potential for using COX-2 or related markers to tailor Aspirin use among patients with newly diagnosed colorectal cancer. Nonetheless, because our data are observational, routine use of Aspirin or related agents as cancer therapy cannot be recommended, especially in light of concerns over their related toxicities, such as gastrointestinal bleeding."

Some tumours will continue to grow despite taking the drug, the study's authors warned.

'Wonderful and easy tool'

The findings are good news, but more research is needed, agreed Barry Stein, a colorectal cancer survivor and president of the Colorectal Cancer Association of Canada.

"Having in the toolbox so to speak, a simple Aspirin to assist in the treatment of the disease, following, for example, the removal of a tumour to prevent its recurrence, is a wonderful and easy tool to have."

In an editorial accompanying the study, Dr. Alfred Neugut of Columbia University Medical Center in New York said the study "comes as close as it can to offering patients a way to help themselves."

Neugut, who was not involved in the study but has done similar research, said if ASA becomes the standard of care in colon care, Cox-2 testing may become routine. It shouldn't add much to the cost of standard tumour tissue testing, he said.

Chan, Stein and Neugut all said colorectal patients should talk to their oncologist before starting to take ASA.

The best defense against colorectal cancer is still early detection of polyps, Stein said.

Approximately 20,000 new cases of colorectal cancer are diagnosed in Canada every year, and roughly 8,500 Canadians will die from the disease every year. One in 14 men and one in 16 women can expect to develop colorectal cancer during their lifetimes.

The study was funded by the National Cancer Institute and the National Institutes of Health.

With files from The Associated Press