TUESDAY, Jan. 18 (HealthDay News) -- A genetic test seems able to identify which people with stage II colon cancer face a higher risk of recurrence, German researchers report.

This would be a huge help to doctors in determining which patients need follow-up treatment after initial surgery and which do not, and it would be an improvement on existing ways to predict recurrence, according to cancer experts.

"Eighty percent of stage II colon cancers are cured by surgery alone," said Dr. Jennifer Obel, an American Society of Clinical Oncology (ASCO) official and an assistant clinical professor of medicine at the University of Chicago, who spoke at a Tuesday news conference to announce the findings. "Only a small percentage develop metastases. We don't want to treat everyone with chemotherapy that will only benefit a few and expose them to unnecessary side effects."

"This is another example of trying to personalize treatment for cancer," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La.

These results and others are scheduled to be presented this weekend at the 2011 Gastrointestinal Cancers Symposium, co-sponsored by ASCO, in San Francisco.

To develop the ColoPrint test, researchers scanned the entire human genome to identify 18 genes that were associated with the risk of a recurrence in patients diagnosed with stage II disease.

In the study, 233 patients who had already undergone surgery for stage II or stage III colon cancer underwent the test and were followed for an average of eight years.

Only 5 percent of patients with stage II cancer identified as low-risk by the test had a recurrence within five years, vs. 20 percent of those who were classified high-risk.

"Patients who ColoPrint identified as high-risk had a 4.1-fold increased risk of developing a distant metastasis compared with those patients who had been identified as low-risk," said study author Dr. Robert Rosenberg, a surgeon and an assistant professor at University Hospital, Technical University, in Munich. "Our studies confirm previous studies. ColoPrint facilitates the identification of patients who might not need additional therapy."

The results are similar to those found in earlier studies of the test, one of which was published in the Journal of Clinical Oncology last year; a larger, prospective trial is now underway.

Another test that looks at 12 genes, called Oncotype DX, is already licensed in the United States., said Brooks. "The question of which test is better is unknown at this time," he added.

Oncotype DX costs upwards of $3,000, and Rosenberg was unable to provide any information on what the cost of the new test, if licensed, would be.

Although Rosenberg did not have any financial disclosures, other authors reported ties with Agendia, which makes the test.

In other news from the conference:

• A Phase II trial in 52 patients with stage II and stage III anal cancer found that chemotherapy with a more targeted mode of radiation (called intensity-modulated radiation therapy or IMRT) had the same benefit as conventional radiotherapy as far out as two years after treatment. IMRT has the advantage of fewer side effects.
• Another Phase II trial showed that the targeted therapy Nexavar (sorafenib) might be useful in patients with gastrointestinal stromal tumors (GIST) who have failed or become resistant to other therapies, particularly Gleevec, a similar targeted therapy; it halted cancer progression in two-thirds of the patients for up to three years. Nexavar did, however, have a number of side effects such as hypertension, which required 63 percent of patients to go to a lower dose of the drug.
• Using positron emission tomography (PET) imaging may help predict the prognosis and guide treatment of patients with locally advanced cancer of the esophagogastric junction. The researchers also found that patients who didn't do well with chemotherapy didn't respond to more radiation, either.

More information

The National Cancer Institute has more on colon cancer.