Were you, or are you, a heavy smoker?
Posted by medconsumers on November 14, 2010
Early this month a federally-funded trial found that screening current or former smokers can reduce their mortality. There were 20% fewer lung cancer deaths among those given low-dose spiral CT lung scans. Consequently, the trial was stopped early, and the results were announced directly to the public on the National Cancer Institute’s (NCIs) website. Until this news broke, no study had proven lung cancer screening can save lives.
The National Lung Screening Trial is sponsored by the NCI and conducted by the American College of Radiology Imaging Network. Participants included more than 53,000 men and women ages 55 to 74 who were heavy smokers. All had smoked at least 30 pack-years—i.e., they had smoked one pack a day for 30 years, or two packs a day for 15 years, or three packs a day for at least 10 years. All were randomly assigned to receive either annual lung scans or standard chest X-rays. None had symptoms of lung cancer when the trial started recruiting in 2002. At the time the trial was stopped, there were 354 deaths from lung cancer in the CT-scanned group and 442 lung cancer deaths in the group given chest X-rays.
The NCI website provides cautions about the new results. For example, there was a 7% reduction in deaths from causes other than lung cancer. But it should not be seen as a call to arms by radiologists eager to screen all middle-aged and older people. Instead, this 7% reduction in deaths is relevant only to middle-aged and older people who have a smoking history similar to that of the study participants. Another caution involves the risks of false-alarm biopsies and treatment of lung abnormalities mistaken for cancer—both can lead to risky lung surgery. (To see how quickly these cautions were ignored, click here.)
The National Lung Screening Trial is not to be confused with another screening study called the International Early Lung Cancer Action Program, or ELCAP. Published in a 2006 issue of The New England Journal of Medicine ELCAP showed that spiral CT scanning can find more potentially curable lung cancers (i.e., early stage). It did not, however, find a reduction in lung cancer deaths in the ten-year duration of this study. Its lead author Claudia Henschke, M.D, took this promising but not definitive finding and went on to claim that most lung cancer deaths could be prevented in heavy smokers through widespread use of CT scans. Over the years, she has gotten a fair amount of media attention with this message despite the consensus among screening researchers that mortality reduction is the only valid outcome for proving a screening test’s worth.
Two years after publication, ELCAP’s results were tarnished by the conflicts of interest associated with its co-authors, Drs. Henschke and David F. Yankelevitz who receive royalties from patents related to screening scans. What’s more, their study was partially funded by $3 million from a cigarette company, as reported in The New York Times (click here).
The newly announced National Lung Screening Trial may have settled the question of whether screening lung scans can save lives, but another controversy has only just begun. Does the benefit of saving one in every 300 heavy smokers outweigh the risks of false-alarms affecting one in four? Because this trial was stopped early, a complete analysis of the harms will not be ready for months.
Maryann Napoli, Center for Medical Consumers©