Lung cancer kills more Americans every year than any other kind of cancer, mainly because doctors don¡t have a reliable way of finding it early. A new nationwide study will test two different methods of looking for tiny lung tumors, to see if either approach can help catch cancer early and reduce the death rate among patients.

Doctors at the U-M Comprehensive Cancer Center (CCC) and other study centers across the country soon will begin making pictures of the lungs of smokers and ex-smokers, using either a chest X-ray machine or a CT (“cat”) scanner. Then, they¡ll track participants¡ health for several years, looking yearly for signs of lung cancer.

By the end of the study, they¡ll be able to tell whether regular chest X-rays or CT scans had any effect on the participants¡ lung cancer detection and mortality rates. This might help determine whether all smokers and ex-smokers should get their lungs scanned regularly, or whether scientists need to keep looking for better ways of finding lung cancer in its treatable early stages.

“The trial will recruit 50,000 patients, of which 1,000 will be specifically recruited here,” says Dr. Ella Kazerooni, director of thoracic radiology at U-M Health System and a member of the CCC. “We¡re looking for men and women aged 55 to 74, who are current and former smokers. Former smokers must have quit within the last 15 years.” Smoking is by far the biggest risk factor for lung cancer, causing 87 percent of cases.

The study is needed because of the huge death toll that lung cancer takes every year†about 157,400 Americans, more than the number that die from prostate, breast, colon and ovarian cancer combined†and because of claims that have been made about the power of new spiral CT machines to detect lung cancer, Kazerooni says.

“In the last few years, CT scans have been shown to pick up small cancers, and it¡s become much easier to see those small cancers with a CT scan than with a chest X-ray,” she says. But, she adds, there isn¡t enough proof to say that CT scans help reduce the lung cancer death rate.

Some doctors worry that, because normal tissue can look suspicious on a high-quality spiral CT scan, the scans will cause needless worry and will lead people to have tests or surgery that could harm them. To settle the debate, the National Cancer Institute and the American College of Radiology Imaging Network are sponsoring the study, called the National Lung Screening Trial.

Participants will be assigned to chest X-rays or CT scans at random. They must have no history of lung cancer, but they must be heavy smokers or former heavy smokers.

The risk of lung cancer goes up with the number of cigarettes smoked per day. Participants who smoke and want to quit will receive referrals to smoking cessation programs.

Participants will have spiral CT scans or X-rays each year for the first three years, and will be surveyed about their health and quality of life every six months for up to eight years, which is enough time to see if there are death-rate differences between the two groups. If an X-ray or CT scan finds a suspicious area on a participant¡s lungs, he or she will be referred for further testing and, if needed, treatment.

Despite lung cancer¡s wide reach and deadly toll, doctors don¡t have the same kind of detection systems for it as they have for other, less common or less deadly cancers.

“People may be familiar with mammography, used to screen for breast cancer, or physical exams, blood tests and endoscopy that are done to look for prostate cancer or colon cancer,” Kazerooni says. “But currently, there is no way to screen for lung cancer.”

To learn if you are eligible to participate in the study, call (800) 742-2300 and enter 6520, or visit http://www.cancer.med.umich.edu/lung.htm.