Patients with colorectal cancer whose tumors carry a mutation in a key gene can benefit from aspirin therapy, according to a study by scientists at the Dana-Farber Cancer Institute in Boston, Massachusetts.1

The study of more than 900 patients with colorectal cancer found that in patients whose tumors had a mutation in the gene PIK3CA, aspirin therapy led to a large increase in survival. Specifically, 5 years after diagnosis, 97% of patients taking aspirin were still alive, compared with 74% of those who were not using aspirin. The medication had no effect on 5-year survival rates in patients without the PIK3CA mutation.

Shuji Ogino, MD, PhD, the study's senior author, notes that researchers have for the first time shown that a genetic marker can help physicians determine which colorectal cancer patients can benefit from a specific therapy. He adds, however, that the results must be confirmed by future studies.

Aspirin is often prescribed for patients with colorectal cancer but, until now, physicians have been unable to predict which patients would benefit. This study indicates that aspirin is effective in the 20% of patients who carry this mutation. It may still be used in the remaining patients, but it is less likely to have an impact and can have side effects such as ulcers and stomach bleeding.

For the study, researchers gathered data on 964 patients with rectal or colon cancer from the Nurses' Health study and the Health Professionals Follow-Up Study, both of which are long-term tracking studies of tens of thousands of people. Dr. Ogino calls the research “molecular pathological epidemiology,” because it combines the study of disease-related genes and research with large populations of people. Such work is a hybrid of 2 frontiers in cancer research that may lead to important new discoveries for patients, he says.

The study was prompted by prior research indicating that aspirin blocks an enzyme called PTGS2, which causes slowing in the signaling of another enzyme, PI3K. As a result, investigators hypothesized that aspirin could be effective against colorectal cancers in which the PIK3CA gene is mutated, because it provides a subunit of PI3K.


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