The study of 900 patients carried out by the Dana-Farber Cancer Institute, an affiliate of Harvard Medical School, found that the painkiller produced a "sharp jump in survival" among certain patients.

"For patients whose tumours harboured a mutation in the gene PIK3CA, aspirin use produced a sharp jump in survival," with 97 percent of those who took aspirin still alive after five years, compared with 74% who did not take it, researchers said.

The drug had no impact on survival rates among patients without a PIK3CA mutation, they added, in a news release accompanying the publication of the study in the New England Journal of Medicine.

"For the first time we have a genetic marker that can help doctors determine which colorectal cancers are likely to respond to a particular therapy," said lead author Shuji Ogino, of the Harvard School of Public Health.

He added that more research must be done before the findings can be considered definitive.

Some 20 percent of colorectal cancer patients have tumours with the mutation, the study said, adding that patients without the mutation can take aspirin, but it can sometimes lead to gastrointestinal ulcers and stomach bleeding.

Colorectal cancer is one of the world's deadliest diseases. The National Cancer Institute expects some 140,000 Americans to be diagnosed with the disease and some 50,000 to die from it this year alone.