Test may predict cancer relapses

Scientists have created a gene profiling test that may someday help reveal which people with early lung cancer are likely to suffer a relapse and would benefit most from chemotherapy.

Separately, other researchers found that several new tumor profiling tests for breast cancer, including two already in general use, are similar in accuracy and should allow many women to avoid unnecessary chemo.

The lung cancer one needs far more testing, but is "breakthrough research" building on years of work to develop personalized cancer treatments, said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society.

Its accuracy so far — about 80 percent — is "better than what we have, but it's not as good as we would like," said Lichtenfeld, who had no role in the research.

Both studies were reported in today's New England Journal of Medicine.

Treatment guidelines for cancer have been relatively crude — based on a tumor's size, whether it has spread, and other characteristics.

As a result, many women with early breast cancer get chemo even though the vast majority would do fine without it. It is the opposite with early-stage lung cancer: Even though about a third of patients will get worse and die, few get chemo because doctors can't tell which ones will benefit, and the treatment itself carries risks. Chemo can damage the liver, heart and other organs, and in some cases can kill.

Doctors hope that growing knowledge about the genes fueling these cancers will lead to better ways to tell who really needs chemo. The newly emerging tumor profile tests are tools to let them do that.

To develop the lung cancer one, Duke University researchers examined 198 tumor samples and analyzed 133 genes whose activity correlated with how aggressive the cancer was.

"It's a fingerprint unique to the individual patient (that) predicts survival chances," said lead researcher Dr. Anil Potti.

Patients were scored as having a low or a high risk of recurrence based on the test, and results were compared to what actually happened to them.

The test was 93 percent accurate on the half of patients whose tumor samples came from Duke and 75 percent accurate on the rest. Current best tests to estimate risk based on tissue characteristics are about 60 percent accurate, Potti said.