People who carry a particular mutated gene linked to 15% to 20% of colorectal cancers saw greater benefit when taking aspirin than those without the mutation, researchers found. The mutation in the PIK3CA gene could be used as a biomarker to spot patients who are more likely to respond to aspirin, they say.
Aspirin is a candidate for adjuvant therapy beside the usual bowel cancer treatments. But colorectal cancer comprises several different diseases, and patients with particular genetic traits respond differently to aspirin.
Survival rates with aspirin are linked to the expression of one such biomarker, the enzyme PTGS2, by tumours. But the results of immunological tests for this marker varied between laboratories, researchers said. This means other biomarkers are needed to identify more consistently those patients who will respond best to aspirin.
In the study, an international team of researchers tested for the presence of the PIK3CA mutation in the DNA of 964 patients with rectal or colon cancer, and compared this with data on aspirin use after diagnosis and survival rates.
They found that patients with the PIK3CA mutation who took aspirin regularly had an 82% lower risk of dying from their cancer than those who did not take aspirin. But patients without this mutation saw no benefit from taking aspirin.
Study authors said the finding should be interpreted with caution, as there were small numbers of deaths in the study, and said it needed to be confirmed by further work.
They concluded: 'PIK3CA mutation may serve as a tumour biomarker that predicts the response to the initiation of aspirin therapy in patients with newly diagnosed colorectal cancer.'
- NEJM 2012; 367: 1596-1606