This story concisely reports the announcement that the long-anticipated National Lung Screening Trial indicates that heavy smokers who were offered a certain type of CT scan were less likely to die of lung cancer than similar smokers who were offered chest x-rays. It includes valuable comments that help readers understand what was found and, more importantly, some of the limitations on what is known.
However, the lead sentence skews the story by highlighting that researchers saw a 20 percent relative difference in lung cancer death rates, while failing to make it clear that the absolute difference in death rates was much less than one percent, because of the small number of few lung cancer deaths in either the CT (354 or 1.32%) or x-ray (442 or 1.65%) group compared to the size of the total trial population (about 53,500). The National Cancer Institute reported that 300 smokers would have to undergo screening in order for one life to be extended. Readers should have been shown that aspect of the results.
Putting a spotlight on relative differences in rates usually magnifies the effects of an intervention. Absolute numbers – and the number of people that need to undergo the intervention in order for at least one to benefit – should get at least equal billing in order to put trial results into perspective.
Mixed bag and, in the end, not specific enough to warrant a satisfactory score.
The story does say that a nationwide lung cancer screening program would be “enormously costly,” and it does mention that screening leads to additional tests and treatments. But what does “enormously costly” mean? And how much could those additional tests and treatments cost?
The story doesn’t tell readers that this type of CT scan costs about $300 (or that the trial participants each received about $900 worth of scans) and that this type of screening is generally not covered by insurance.
This story might have met this criterion if not for a misleading lead sentence. Researchers did announce that the heavy smokers in this trial who were offered CT scans had a 20 percent lower rate of death from lung cancer than those offered chest x-rays. The story does report the total number of deaths in the body of the story (354 vs. 442), but it does not point how that because so many smokers were in this trial, the lung cancer death rate in each group was less than 2 percent. That context is important, because while the relative difference in death rates is indeed 20 percent, the absolute difference is less than one-third of one percent (1.32% vs. 1.65%). A letter sent by the National Cancer Institute to trial participants points out that based on these results, 300 heavy smokers would have to be screened in order to extend a single life. Those statistics would have helped readers put the results in perspective.
The story does include valuable comments from one of the researchers about how much more analysis and study is needed in order to understand whether and for whom this sort of screening might be beneficial.
Another problem with the lead sentence is that it is not quite accurate to say that “annual CT scans” produced this result, since the trial didn’t offer ongoing annual screening, but rather three scans done at one-year intervals and then no more.
The final paragraph of the story points out that there is a risk of harms from the radiation used for the CT scans and that the scans cause false positives and may lead to tests and treatments done on people who actually don’t have dangerous tumors. We wish some attempt had been made to quantify these harms – even if it meant drawing from past research – but we’ll give the story the benefit of the doubt.
The story describes the trial, including who was enrolled, that they were screened by either chest x-rays or low-dose CT scans, and that they were followed for up to five years. It also notes that early trials of CT scanning of smokers had failed to demonstrate a difference in death rates.
The story reports that this study involved current and former heavy smokers. However, near the end of the story there is a reference to “more than 80 million current and former smokers in the United States.” It is not clear whether this number is meant to be an estimate of the number of people who smoked as heavily as those included in this trial. (The study enrolled only people who had smoked at least 30 pack-years, which is calculated by multiplying the number of years of smoking and the number of packs smoked per day. For example, 30 years of smoking a pack a day or 15 years of smoking two packs a day would each have 30 pack-years of smoking experience.)
There is an independent source and the story reports that the trial was government-financed.
However, the story does not tell readers that the independent source, Dr. Claudia Henschke, has been a loud critic of this trial. Dr. Henschke has been criticized both for making claims about benefits of CT screening that went beyond the available evidence, for having ties to a leading manufacturer of CT scanners, and for taking funding from a tobacco company. She should have been identified as someone who has frequently clashed with those who have supported this trial.
The story reports that no other screening method (including chest x-rays) has been shown to reduce lung cancer death rates among current and former smokers. However, many health experts are concerned that lung cancer screening could lull smokers into a false sense of safety. This story fails to mention quitting smoking as a way to reduce the risk of death. Nonethless, we’ll give the story the benefit of the doubt on this criterion.
While it may seem obvious that CT scanning is widely available, this trial used a specific and rigorous protocol for selecting the type of low-dose CT scanners used, how they were maintained and operated, as well as certifying the training and practices of the radiologists who interpreted the scans. The sort of CT machines, operators and radiologists generally available to smokers may not meet the demanding standards of this trial and thus may not be able to match the results.
The story recaps some of the history of research on screening for lung cancer and quotes one of the researchers saying, “This is the first time that we have seen clear evidence of a significant reduction in lung cancer mortality with a screening test in a randomized controlled trial.”
The story is not based on a news release.