Gene test predicts risk of colon cancer return

By Deena Beasley

LOS ANGELES, May 14 (Reuters) - A genetic test that predicts whether colon cancer will return in certain patients will have a significant impact on treatment options, researchers said on Thursday.

Molecular diagnostics company Genomic Health Inc (GHDX.O) said last month that a pivotal trial of its OncoType DX colon cancer assay showed that it could predict cancer recurrence risk but did not meet a secondary goal of predicting a patient's response to standard chemotherapy after surgery.

The company already makes a widely-used Oncotype DX test for breast cancer. "This is the Oncotype DX test for colon cancer," Dr. Richard Schilsky, president of the American Society of Clinical Oncology and blood cancer specialist at the University of Chicago, said in an interview.

Schilsky said 25 percent of colon cancer patients have node-negative stage II colon cancer, meaning the tumor has spread a little in the colon but not to nearby lymph nodes.

Eighty percent are cured by surgery but it is impossible to predict. "We don't have a good way of telling who is likely to relapse," Schilsky said. So it is not clear who should get chemotherapy to prevent the cancer from coming back.

The test looked at a panel of 18 different genes in 1,851 colon cancer patients.

For patients in the low-risk group, the chance of recurrence three years after surgery was 8 percent but patients in the high-risk group, according to the test results, had a 21 percent chance of recurrence.

"The icing on the cake would be if we had an additional test that showed which subgroup chemotherapy will work in and which it won't ... We will be investigating. We'll be looking at other gene signatures," study author Dr. David Kerr, professor of cancer medicine at the University of Oxford, said during a press briefing.