A new test may reduce the need for expensive and invasive procedures to diagnose lung cancer in some patients. Momen Wahidi, MD, an interventional pulmonologist at Duke -- one of the few centers in the U.S. administering the test -- said, “It’s a useful test when done in the right way for the right population.”
Diagnosing Lung Cancer
When chest imaging studies identify a suspicious lung spot, a thin tube called a bronchoscope is inserted into the nose or mouth to reach the lungs. Tissue samples are obtained, and then sent to a lab to look for the presence of cancer cells. Unfortunately, the test isn’t always conclusive.
“We only get definitive answers 60 to 70% of the time,” said Dr. Momen Wahidi, MD, an interventional pulmonologist at Duke. Sometimes the cancerous tissue is too deep in the lungs for the bronchoscope to reach it.
When lung cancer can’t be ruled out following the bronchoscopy, the next step is to decide on further invasive tests. One option involves the placement of a long, thin needle through the chest wall. The procedure, which is called transthoracic needle aspiration, is performed by a radiologist, who uses CT images to guide the placement. Lung collapse can occur in 15% of cases.
Another option is to perform a surgical lung biopsy through an incision made in the chest. Lung collapse, bleeding and infection occur in 5% of cases.
Test Looks for Cell Changes that Indicate Cancer
The new test can help eliminate the need for the additional invasive procedures. When performing the bronchoscopy, a small brush-like device sweeps up cells from the patient’s normal-appearing airways. “The brush is put into a plastic bullet, which is sent to a lab for analysis,” explained Wahidi. There, the cells are evaluated for genetic alterations which assist in determining whether the lung growth is cancerous.
Negative Results Indicate Low Chance of Cancer
“If the genetic test is negative a patient’s likelihood for having cancer is very low,” said Wahidi. This is supported by a study published in the New England Journal of Medicine.
“This genetic test makes us feel confident that the negative biopsy results truly reflect the benign nature of the lung spot rather than our inability to reach it. When the genetic test is negative, there is no need for additional invasive testing. We will likely take a conservative approach and repeat another chest CT scan on a later date.”
If the test result is positive, a biopsy is needed to make a definitive cancer diagnosis.
Who Will Benefit?
The genetic test is not for everyone. “It’s a useful test when used on the right population,” Wahidi said.
“If I know a person is at high risk for cancer, the test is not useful,” he said. It is more likely to be used in people who are at intermediate risk for cancer. Lung cancer risk is determined by a variety of risk factors including smoking, age, history of cancer and the shape and size of the lung spot. “A lot of people we see with spots on their lungs are in this intermediate category.”