The study, published in the New England Journal of Medicine, used data from 964 patients with colorectal cancer. Ninety-seven percent of those with the mutation in the PIK3CA gene who had also been taking aspirin were still alive five years after diagnosis. This was in comparison with a 74 percent survival rate among patients with the mutation who were not taking the drug. Conversely, aspirin did not impact survival rate for patients not possessing the gene mutation.
Between one in six and one in five colorectal tumours are thought to carry the PIK3CA mutation.
'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 senior author Dr Shuji Ognio of the Dana-Farber Cancer Institute and Brigham and Women's Hospital in Boston, USA.
Aspirin is already frequently prescribed for colorectal cancer patients but doctors cannot predict which patients might benefit. This study suggests that the survival benefit is limited to those patients whose tumours have the PIK3CA mutation.
If so, then a gene test done before beginning could enable more selective prescription so that patients who do not have the mutation would be spared the risks, which include gastrointestinal ulcers and stomach bleeding, of aspirin therapy.
Speaking to CNN, Dr Ernest Hawk, vice president for cancer prevention and population sciences at the MD Anderson Cancer Center in Houston, USA, who was not involved in the study, called the research 'very compelling'. CNN reports that Dr Hawk 'believes that testing patients for this particular genetic mutation should be completely doable, since most pathology labs today now have the ability to test the DNA of tumours'.
However more work would need to be done before aspirin could be ruled out as therapy for patients whose tumours do not carry the mutation.
'Although these data are exciting and intriguing, they need to considered as preliminary and will require validation in prospective studies, given the small number of patients included in this study', writes Dr Boris Pasche, director of haematology/oncology at the University of Alabama, USA, in an editorial accompanying the study.
Were the results to be echoed by larger studies, 'Aspirin [could] become one of the oldest drugs to be used as a 21st-century targeted therapy', Dr Pasche concludes.