Gene Test May ID Lung Cancer Spread
Researchers Say Test May Let Some Patients Avoid Unnecessary Chemotherapy
May 16, 2008 -- A test that characterizes early lung tumors by their genetic fingerprint may help identify patients whose cancer is most likely to spread, researchers report.
The powerful genetic tool may help spare many early-stage lung cancer patients with less aggressive disease from unnecessary chemotherapy -- and all its unpleasant side effects, says researcher Ming Tsao, MD, professor of laboratory medicine and pathobiology at the University of Toronto. "Not all patients benefit from chemotherapy, and not all patients require chemotherapy after surgery."
"If validated, this genetic signature could potentially identify those patients who have aggressive cancer and who would benefit from chemotherapy and perhaps just as importantly, those patients not likely to benefit," he tells WebMD.
The genetic test is being developed for people with non-small-cell lung cancer, the most common type of lung cancer.
The findings are scheduled to be released at the annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago.
Gene Test Predicts Risk of Lung Cancer Recurrence
First, the researchers used a commercially available gene chip to analyze banked tumor tissue samples from patients who did not receive chemotherapy after surgery for non-small-cell lung cancer.
They were able to identify a set of 15 genes that discriminated between those at high risk and those at low risk of recurrence -- regardless of a patient's age, tumor stage, or other characteristics. Some of these genes are known to play important roles in cell growth and death, or regulate other genes involved in cancer.
"The 15-gene signature was able to classify patients into two groups with very different risks of recurrence: 31 patients with a very good prognosis and a very low risk of recurrence, and 31 patients with a very poor prognosis and a very high risk of recurrence," Tsao says.
The researchers then tried out the test on patients who did receive chemotherapy after surgery. They found that 67 patients classified at high risk of recurrence by the test did indeed benefit from the chemo; they were 67% less likely to die than if they didn't receive the anticancer drugs.
Sixty-six patients who were classified at low risk of recurrence, on the other hand, gained no benefit from chemotherapy, Tsao says.
Similar Test Available for Breast Cancer
Richard L. Schilsky, MD, president-elect of ASCO and professor of medicine at the University of Chicago, says this is "a very important and provocative paper."
Schilsky tells WebMD: "We know that chemo after surgery improves survival for patients with many common solid tumors, including breast, colorectal, and non-small cell lung cancer. But we also know that not every patient needs it; across the board, about 50% to 65% of people with solid tumors are cured by surgery alone. So what we would really like is some type of test that tells us who is at very high risk of recurrence and therefore who needs treatment, and that is exactly what this research is aiming to do."
Schilsky notes that a similar test, known as Oncotype DX, is already commercially available for women with some types of breast cancer. Researchers recently reported that the test has significantly cut down on the number of women who are unnecessarily undergoing chemotherapy after surgery to remove their breast tumors.