The quest for a simple diagnostic test of lung cancer is beginning to pay off, researchers said here today.

A scraping of cheek cells contains a “clear signal” of malignancy-associated cellular changes that indicate lung cancer, reported Bojana Turic, M.D., of Perceptronix, Inc., at CHEST 2005, the annual meeting of the American College of Chest Physicians. But the sensitivity and specificity of the test are not good enough for prime time yet.

Her Vancouver-based company, a spin-off from the public-sector British Columbia Cancer Agency, has spent the past two years on prospective clinical trials evaluating changes found in the sputum of 2,400 participants, all at high risk for lung cancer.

As part of the studies the researchers also collected buccal cells from 570 participants and subjected them (as well as cells from sputum) to a novel test involving a proprietary stain for malignancy-associated changes and cytometric analysis using new algorithms, Dr. Turic said.

“The signal that we detect is strong in sputum, as we would expect,” she said. “It was a little bit weaker in buccal scrapings but it still exists.”

The malignancy-associated changes that the test detects, she said, are thought to be the reaction of normal cells to the presence of cancer cells. Cells in sputum, derived from the lungs, would be expected show more changes than cells from further away.

Of the 570 participants, 240 were later shown to have lung cancer, Dr. Turic said. The buccal-cell test correctly identified half of those, she said, but had a false-positive rate of 30%, she said.

“The test is quite easy to administer, it’s a low-cost test, and it does have information that a physician can use, in combination with other tests,” she said. “The test really gives you the risk assessment—whether a patient should go forward for follow-up.”

Until the sensitivity and specificity are improved, she said, the test won’t be offered for immediate clinical application. “We’re still crunching the data,” she said, and then regulatory agencies will have to approve the test before it will be available to physicians.

The study is “intriguing preliminary data” said Michael Alberts, M.D., chief medical officer of the F. Lee Moffitt Cancer Center in Tampa, Fla. Dr. Alberts is also president of the American College of Chest Physicians.

“The scientific community has not been able to find (a simple test for lung cancer),” he said. Dr. Turic’s test is an “exciting first step,” he said.

Dr. Turic said the advantage of the test is its simplicity. It’s easier than inducing sputum, which requires special equipment and is a cumbersome process.

“The test is quite easy to administer, it’s a low-cost test, and it does have information that a physician can use, in combination with other tests,” she said. “The test really gives you the risk assessment - whether a patient should go forward for follow-up.”

On the other hand, she said, it’s still not clear how the malignancy-associated changes found with the test are related to the biology of lung cancer, because the study only took a single sample from each subject, rather than multiple samples over time.

Until the sensitivity and specificity are improved, she said, the test won’t be offered for immediate clinical application. “We’re still crunching the data,” she said, and then regulatory agencies will have to approve the test before it will be available to physicians.

But in the long term, Dr. Turic said, she envisions cheek scrapings as part of a program of preventive care, much as Pap tests are used in preventive care for cervical cancer.

Source: CHEST 2005