CT scans catch tumors
Early detection of lung tumors by using advanced CT imaging yields an estimated 10-year survival rate of more than 90 percent, and smokers and others at high risk should be routinely screened for the disease, according to a report today in the New England Journal of Medicine.
The study of more than 30,000 patients shows that the scans are as cost-effective and beneficial as mammography is for breast cancer, the researchers said.
“This is compelling evidence that you can use CT screening to find lung cancer … and when you find it early and take it out early, you can cure a high percentage of patients,” said Dr. Claudia I. Henschke of Cornell University’s Weill Medical College in New York, who led the study.
CT scans produce a sharp, three-dimensional image of the chest that allows physicians to detect much smaller objects than can be seen on a conventional chest X-ray.
Laurie Fenton, president of the Lung Cancer Alliance, joined Henschke in calling for routine screening. The results “flip lung cancer survival statistics on their head,” she said.
Currently, only about 5 percent of the 174,000 lung cancer patients diagnosed each year survive for 10 years. “They are showing 92 percent survival of those with an early disease diagnosis,” she said.
Some cancer experts, however, said that the study does not prove that screening reduces deaths from the disease and that it is too soon to recommend widespread use.
It is possible, that the screening simply revealed many slow-growing or benign tumors that would not have caused problems if they had not been identified, said Dr. David Johnson of Vanderbilt University, past president of the American Society of Clinical Oncology.
Researchers can only identify a definitive benefit if there is a control group that does not undergo CT screening, similar to the placebo group in a drug trial.
“The real gold standard for determining whether screening is useful is whether it impacts on mortality,” reducing deaths, Johnson said. Although the new results are promising, “these data don’t answer that question.”
National cancer organizations currently do not recommend screening for lung cancer, and this study seems unlikely to change that stance.
“Health policy isn’t made on the basis of one study,” said Robert A. Smith, director of screening for the American Cancer Society.
He and other experts agreed that no change in policy is likely until the end of the decade, when results will be available from large trials conducted by the National Institutes of Health and the Mayo Clinic in Rochester, Minn., comparing CT screening to conventional chest X-rays.
The current consensus against screening stems from studies in the 1970s that showed screening with conventional chest X-rays produced no increase in survival because they failed to show many tumors.