Benefit of CT Scans for Lung Cancer Screening Remains Unproven, Says Duke Professor
DURHAM, N.C. -- Using CT scans to screen patients at high risk for lung cancer is an exciting area of research, but this method has not yet been proven to actually save lives, according to Ned Patz, M.D., a professor at Duke University Medical Center.
Patz' assessment is a response to an article in this week's New England Journal of Medicine, published by the International Early Lung Cancer Action Program Investigators.
In the article, researchers concluded that among patients at risk for lung cancer, "such screenings could prevent some 80 percent of deaths from lung cancer." But this conclusion is not supported by the researchers' data, said Patz, a professor of radiology and professor in pharmacology and cancer biology at Duke.
While their study confirms that CT detects small nodules, and that small nodules deemed as early stage cancer are highly treatable, the trial was not designed to determine the effectiveness of CT in reducing mortality among patients at risk for lung cancer, he said. Their findings validate prior studies, but they do not say how patients would have fared if they had not received a CT scan, he said.
As a patient advocate, Patz wants to ensure that CT screening provides more benefit than harm to patients. CT scans can potentially harm patients by exposing them to repeated, unnecessary radiation or unnecessary surgeries that carry substantial risks, he said.
Moreover, detecting early-stage lung tumors does not translate into saved lives, said Patz. Non-aggressive lung cancers can be found during autopsy in people who have died of other, unrelated causes. Treating such individuals with aggressive therapy would unnecessarily expose them to the dangers associated with surgery and the potentially deadly effects of drug therapies.
"Finding a lung cancer when it is smaller does not necessarily mean the cancer is at an earlier stage of development," he said. "The genetic characteristics of a tumor and the patient's unique immune response are more likely to dictate its behavior."
Patz said the New England Journal of Medicine article raises awareness of the potential of CT scans for improving lung cancer diagnosis. But he said the study did not compare the use of CT scans against a control group of patients who received chest X-rays or no imaging at all. Such a comparative study is essential if the medical community is to prove whether CT scans decrease lung cancer deaths, the ultimate goal of a screening program, he said.
Because of these factors, Patz said, it is important to await the results of an ongoing randomized clinical trial comparing chest X-rays against CT before concluding that screening will save lives. The study, called NLST, is being conducted at over 25 sites nationally and is funded by the National Cancer Institute.
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