Posted: Jan 26, 2012 10:55 PM
The hope is that doctors can use that information to figure out which patients might benefit from more aggressive treatment for their early lung cancers.
Lung cancer is one of the most common cancer types. It's also one of the deadliest, even for the lucky few who catch their tumors while they are still small and have not spread.
Unlike stage I breast cancer, which has a five-year survival rate of 88%, stage I non-small-cell lung cancer has a five-year survival rate of 45% to 49%, according to the American Cancer Society.
There are some effective therapies for people with stage I lung cancer that are not always used because it is difficult to identify the best patients for those therapies, Michael J. Mann, MD, a thoracic surgeon and associate professor of surgery at the University of California, San Francisco, tells WebMD.
"Just matching patients to an effective therapy in a slightly more efficient manner would actually improve the survival rate for lung cancer, which is an accomplishment that has eluded medical scientists for three decades," he says.
The test looks at the activity of 14 genes and compares that profile to how those same genes are working in normal tissue.
"We're able to identify a pattern of biology within the tumor, and that pattern of biology tells a huge part of the story as to where that tumor is in the evolution of its aggressive behavior," says Mann, who reported a financial relationship in the company that's developing the test.
Mann says his group wanted to develop a test that doctors could use on lung tissue samples that were handled in the usual way. Usual handling involves dunking samples in harsh preservative chemicals and then sealing them in hot wax, a process that destroys a lot of genetic material.
And they think they have succeeded.
So far, researchers have tried out the test in three different patient populations, representing more than 1,800 people with non-squamous, non-small-cell lung cancer, which is the most common type.
The results have been remarkably consistent.
Patients with tumors that had a high-risk profile as measured by the test also had a high rate of early death. About half of those patients were not alive five years after their diagnoses.
About 42% of patients with tumors that were deemed intermediate risk based on their genetic profile were not alive five years after their cancer was discovered.
And 25% to 30% of patients with low-risk tumors had not survived five years later.
The researchers' results are published in The Lancet.
Researchers say it's not yet clear what this means in terms of treatment.
"That's the $64,000 question," Mann says. "We know that certain subsets of patients who undergo surgery will have increased survival if they get chemotherapy after surgery," he says.
But chemotherapy is not recommended for many stage I non-small-cell lung cancers. Mann thinks that's because the studies simply haven't be able to distinguish high-risk from low-risk patients. He thinks the new test could change that.
Other experts agree.
"In my mind, currently, it's the best of anything I've seen, and it's done in a fashion that could be deployed in the real world," says John L. Minna, MD, a pulmonary oncologist at the University of Texas Southwestern Medical Center in Dallas.
Minna wrote a commentary on the study but was not involved in the research.
He says with more people getting screening tests for lung cancer, having a better way to distinguish high-risk from low-risk patients will be important for making sure people don't get too much or too little treatment for their disease.