David Brown, Washington - A STUDY has found that it is possible to find a large number of "silent" cancers in the lungs of heavy smokers by periodically screening them with CT scans.

When the tumours are then taken out by surgery, most people live five years or more, in contrast to patients whose cancers are found only after they experience symptoms.

The study of nearly 32,000 people in eight countries raises hope that early detection by CT scans might reduce the death toll of lung cancer, much as mammography has done for breast cancer.

But while the research clearly shows the interval between diagnosis and death was longer in screened patients, it does not definitively show they actually lived longer � a subtle difference with huge public health consequences.

Lung cancer kills about 162,000 Americans a year and is the leading cause of cancer death in both men and women. Only 15 per cent of people with lung cancer survive five years from the time the disease is found.

The debate over whether CT scans are useful or a waste of time and money is a matter of great controversy here.

Some, including many treatment advocates, think there is enough evidence now to urge all heavy smokers to get routine CT scans. Others, including researchers and policymakers, say the question will not be settled for five or six years, when other studies are complete.

The research, which appears in The New England Journal of Medicine, is destined to intensify the debate.

"We think this is a breakthrough for lung cancer. I think we have enough data to move forward and apply this to a high-risk population," said Laurie Fenton, president of the Lung Cancer Alliance.

The study began in 1994, screening smokers and former smokers, as well as a few non-smokers exposed to radon, beryllium and other cancer-causing substances.

In all, 31,567 people were screened. In the ensuing years, about 27,000 more scans were done, with some people getting them annually. All were "spiral" or "helical" CT scans in which the machine films the entire chest in the time a person can hold a single breath.

About 13 per cent of the baseline scans and 5 per cent of later ones found abnormalities. Ultimately, 535 were biopsied to see if they were lung cancer � and 484 were. Early lung cancers can usually be cured; the problem is that they are often found only by chance when someone gets a CT scan or chest X-ray for an unrelated reason.
WASHINGTON POST