Medical centers across the country will screen 50,000 smokers in a landmark study to find out whether early detection of lung cancer saves lives, federal health officials announced yesterday.
The $200 million trial sponsored by the National Cancer Institute will compare chest X-rays and spiral CT scanning, a more expensive technique that can detect smaller and therefore less advanced tumors.
"Conventional wisdom suggests that the smaller the tumor when it is found, the more likely the chance of survival, but that remains to be proven," said Dr. Denise Aberle, a UCLA radiologist who is one of the study's principal investigators.
In the trial, volunteers will be randomly assigned to one of the two imaging techniques and screened annually for three years. Participants will then be followed for an additional five years to determine whether either screening method improves survival.
The Johns Hopkins School of Medicine is one of 30 medical centers across the country planning to take part in the trial. Centers will enroll men and women who are current or former smokers and have never had a cancer diagnosis.
"There really hasn't been a major improvement in early diagnosis and even treatment of lung cancer in a half a century," said John R. Seffrin, chief executive of the American Cancer Society, which is helping to promote the trial.
Making headway against lung cancer is important because the disease remains the leading cancer killer in the United States, accounting for 150,000 deaths and 169,000 new cases annually, according to the cancer society.
The CT machines scan the entire chest for about 15 to 25 seconds and construct a three-dimensional model of the lungs. Hospitals routinely use the machines to determine the size of tumors after a cancer diagnosis, though some have begun using them to screen undiagnosed smokers for evidence of early cancer.
Spiral CT scanners can pick up tumors smaller than 1 centimeter in diameter; chest X-rays can identify tumors 1 to 2 centimeters across.
It remains to be seen whether people whose cancers are diagnosed at either stage live longer than those whose cancers are detected later.
It is possible that early detection of lung cancers will lead to surgery and other risky treatments without any reduction in death rates, Aberle said. It is also possible, she said, that aggressive screening will turn up slow-growing cancers that would never kill the patient if left alone. A similar controversy surrounds early detection of breast and prostate cancers.