BETHESDA, MarylandResearchers have begun accruing 50,000 patients for the National Lung Screening Trial (NLST), the much-awaited comparison of the efficacy of spiral CT scans and chest x-rays in reducing lung cancer mortality. Investigators in the 8-year, National Cancer Institute-supported study expect to complete enrollment within 2 years. Enrollment will be aided by a $5 million educational campaign funded and organized by the American Cancer Society (ACS), and aimed at encouraging current and former cigarette smokers to participate in the trial.
"We estimate that about 169,000 men and women will be diagnosed with lung cancer in 2002, and about 155,000 deaths will occur," said co-principal investigator John K. Gohagan, PhD, chief of the NCI Early Detection Research Group. He emphasized that the tests being studied are the only accepted and proven screening tests for lung cancer that could reduce mortality.
Thirty medical centers throughout the United States will take part in the $200 million randomized, controlled study. Results from earlier spiral CT studies, conducted by a collaboration of New York City researchers and a group in Japan, have indicated that spiral CT, also known as helical CT, can detect tumors much smaller than 1 cm. Chest x-rays can reveal tumors as small as 1 to 2 cm in size. However, there is no scientific evidence showing that either chest x-rays or spiral CT screening has a positive effect on lung cancer mortality.
Despite this lack of mortality evidence, the potential for finding lung cancer at a size that theoretically should increase a patient’s chances of surviving the disease has led many present and past smokers to have spiral CT scans. A number of specialized centers have opened to meet the demand, which has disturbed oncologists and public health officials.
"In many instances, those individuals, in good faith, are having screening tests done on the assumption that they are helping themselves from a medical perspective," said Denise Aberle, MD, professor and chief of thoracic imaging, UCLA, and the NLST’s other co-principal investigator.
"The reality is we don’t know that the screening test is actually of benefit. We don’t know whether that test may actually expose them to downstream complications of additional diagnostics, which have their own morbidity and potential mortality that may do them more harm than the screening test itself," she said.
NCI has sponsored three previous studies, which began in the 1970s, examining the use of chest x-rays and sputum cytology as potential screening tests for lung cancer.