New Test for Lung Cancer Could Detect Disease 2 Years Before Tumors Appear

A preliminary study of a new test for lung cancer found that the test could detect the disease’s presence an average of two years before tumors first caused symptoms or showed up on X-rays, according to a report published Tuesday in the Journal of Clinical Oncology.

Lung cancer, the most common fatal cancer in both sexes, is expected to kill 139,000 Americans this year, according to the American Cancer Society. Currently, about 90% of lung cancer patients die within two years of diagnosis.

A major reason for this high mortality rate is the fact that most lung tumors have spread to other organs of the body by the time they are discovered.

If the new test’s promising performance is confirmed in larger studies, it could give doctors the first means of detecting lung tumors at a very early stage, perhaps leading to the development of more effective treatments for the disease.

“We’re excited about it, but it’s very, very preliminary,” said Dr. James L. Mulshine, chief investigator of the National Cancer Institute’s Navy Medical Oncology Branch and a principal author of the study. “We’re five to 10 years away from being in a position to help anybody.”

The test uses monoclonal antibodies, chemicals produced by the immune system that react with certain proteins often present on cancer cells. Devised by researchers at the National Cancer Institute and Johns Hopkins University Medical School, the test contains two separate antibodies, derived from mouse immune cells, that react against different varieties of human lung tumors.

Mulshine said the proteins detected by the antibodies are present on cells during fetal development but are normally lost as the cell matures. During the development of a cancer, a process that is thought to take 10 to 20 years, growth mechanisms within the cell are turned on and it begins to manufacture the proteins again.

The test is performed on a specimen of sputum or mucus that a patient coughs up. Such sputum normally contains cells that line the bronchi, the branching tubes that carry air to and from the lungs.

The sputum is spread on a glass slide and treated with solutions containing the antibodies. If cells in the sputum contain the proper proteins on their surfaces, the antibodies stick to the proteins and cause the cells to show up when a special stain is applied to the slide.

Researchers tried the antibody test on 69 sputum specimens that had been saved from patients in a previous study done at Hopkins in the 1970s. All of the specimens had shown “atypical” cells, and 26 of the patients had gone on to develop lung cancer.

Specimens from 20 of 22 patients who had developed cancer stained positively using the new test, and 35 of 40 specimens from patients who did not develop cancer stained negatively. The remaining seven specimens could not be tested because the cells they contained were not well preserved.

Mulshine said the next step will be to study the test in a larger number of patients from the Lung Cancer Study Group, a multi-hospital research group, to see if its accuracy holds up in patients whose sputum does not show atypical cells.

The group will evaluate the new test in patients who have had lung tumors removed surgically. Such patients have between a 3% and 5% annual chance of developing a second lung tumor. Mulshine estimated that it would take four or five years to complete that study.

If the test proves able to detect very early lung tumors, the next challenge will be to test the effectiveness of early treatment using surgery, chemotherapy or newer techniques such as laser therapy, Mulshine said.

“What we’re doing here is looking at cancer before there’s even a chance to be a lump,” he said. “If we can do this on lung cancer, we’re going to start reappraising (antibody tests for) a whole variety of other solid tumors,” such as colon cancer and breast cancer.