Gene Test Predicts Return of Colon Cancer
Test Called Oncotype DX Could Help Patients Decide if Chemotherapy Is Needed
Risk of Cancer Recurrence continued...
Depending on the activity of the 12 genes, participants were assigned a recurrence score and classified as being at low, medium, or high risk of recurrence.
The study showed that the recurrence score accurately predicted the risk of cancer coming back, Kerr says.
People in the low-risk category had only about a 12% chance of having a recurrence at three years, the study showed. But people who fell into the high-risk category had a 22% chance of having recurrence.
The Chemotherapy Dilemma
The recurrence score can be used to guide the difficult decision of whether to have chemotherapy after surgery, Kerr tells WebMD.
In patients with low recurrence scores, "I don't think any doctor would recommend chemotherapy. The side effects and hassle of chemotherapy outweigh the benefits," he says.
But in patients with high recurrence scores, chemo can cut the risk of cancer coming back by another 5%, Kerr tells WebMD. "We know from other work that patients are willing to accept side effects given that degree of benefit."
What about patients at intermediate risk? There, the answer is less clear, Kerr says. "In my clinical practice, I find that younger medium-risk patients tend to say the benefits of chemo outweigh the risks. Those age 70 and older say, 'Thanks, but no thanks.'"
Schilsky tells WebMD that the new test is a good step forward. But he says he would like to see it better discriminate between patients at low and high risk of recurrence.
Kerr says studies to refine the test, incorporating more genes that may be involved in colon cancer and following larger numbers of patients, are under way.
His team also hopes to develop a score to predict not only whether a patient will suffer a recurrence, but also whether chemotherapy will actually work. Their first attempt at such a test failed, largely due to too few patients, Kerr says.