But, Sargent added, "we felt that in order to really recommend this in clinical practice, we needed to validate it."
The new study analyzed data from 1,027 patients in the United States as well as Canada, France and Italy who had participated in previous trials. Sixteen percent had dMMR.
"The goal was to validate that the 15 percent of patients who have defective mismatch repair did not receive any benefit from 5-FU therapy, and that is indeed exactly what we found," Sargent said.
"We now feel this is appropriately validated for clinical use," he added.
In fact, there is already a simple test for this type of cancer.
"The test is available and, in a patient with stage 2 disease being considered for treatment with chemotherapy, we think that this test would be useful," Sargent said.
More information
The National Cancer Institute has more on colon cancer.
