Large US trial finds screening of heavy smokers reduces lung cancer deaths
Current or former heavy smokers who are screened with low-dose spiral computed tomography (CT) scanning could be up to 20 per cent less likely to die from lung cancer than those screened by single view chest x-rays, show results from a decade-long clinical trial by the US National Cancer Institute (NCI).
Early results from the National Lung Screening Trial (NLST), of more than 53,000 people, were published in November 2010.
Now, scientists have published a full analysis in the New England Journal of Medicine, which provides further evidence of fewer deaths from spiral CT, which uses x-rays to obtain a multiple-image scan of the entire chest.
Dr Denise Aberle, national principal investigator for 23 of the 33 sites involved in the study and a researcher at the University of California, Los Angeles' Comprehensive Cancer Centre, said: "These findings confirm that low-dose CT screening can decrease deaths from lung cancer.
"This study also will provide us with a road map for public policy development in terms of lung cancer screening in the years to come."
The trial involved 53,454 men and women, aged 55 to 74, current or former heavy smokers with no history of lung cancer.
Participants were recruited in August 2002 and were screened each year for three years, either by low-dose spiral CT or standard chest x-rays.
They were followed for up to five years. According to the full analysis, there were 20 per cent fewer lung cancer deaths among patients who were screened with low-dose spiral CT than with chest x-rays.
In addition, the overall death rate from all causes was 6.7 per cent lower in the CT scan group.
Dr Aberle noted: "The NLST cannot answer all of the important questions about screening that will be important for implementation. However, the NLST data can be used to develop mathematical models to determine how long screening should be performed and how often.
"In addition, the data can be used to determine whether other groups at risk of lung cancer, such as light smokers, those with family histories of lung cancer or individuals with lung diseases like emphysema, would benefit from screening with spiral CT scanning."
Professor Stephen Duffy, Cancer Research UK's screening expert, said: "An intervention like this that can reduce deaths from lung cancer is exciting news. However, CT screening for lung cancer does have its financial and human costs. In particular, this study suggests that lots of people who have a suspicious scan may turn out not to have cancer. Research going on across Europe will help by pinpointing the type of people for whom the benefits of screening outweigh the costs and risks.
"We should also continue to reduce the health burden of tobacco - after all, smoking causes nine out of ten cases of lung cancer, and increases the risk of dozens of other cancers. But this doesn't detract from the importance of these results, which take us closer to a new and effective tool in the fight against lung cancer."
Writing in an accompanying editorial, Dr Harold Sox, from Dartmouth Medical School in the US, said that policymakers should wait for further research on cost-effectiveness and the amount of over-diagnosis - when a cancer is detected that is so slow-growing that it is likely to be harmless - before introducing national lung cancer screening programmes.
But, he said this latest study provides doctors and patients with "much better information than before on which to base their discussions about lung cancer screening".
He added: "The findings of the NLST regarding lung cancer mortality signal the beginning of the end of one era of research on lung cancer screening and the start of another. The focus will shift to informing the difficult patient-centred and policy decisions that are yet to come."