National Lung Screening Trial

The National Lung Screening Trial was a United States-based clinical trial which recruited research participants between 2002-2004.[1] It was sponsored by the National Cancer Institute and conducted by the American College of Radiology Imaging Network and the Lung Screening Study Group.[1] The major objective of the trial was to compare the efficacy of low-dose helical computed tomography (CT screening) and standard chest X-ray as methods of lung cancer screening.[2] The primary study ended in 2010, and the initial findings were published in November 2010, with the main results published in 2011 in the New England Journal of Medicine.

National Lung Screening Trial
other namesNLST, NCT00047385
sponsorNational Cancer Institute
number of participants53,454
startAugust 2002
endOctober 2010
primary completionOctober 2010

The trial led to a recommendation in the United States in 2013 that CT screening be used on people at high risk for developing lung cancer in an effort to detect the cancer earlier and reduce mortality.[3] In December 2013 the U.S. Preventative Services Task Force (USPSTF) changed its long-standing recommendation that there is insufficient evidence to recommend for or against screening for lung cancer to the following: "The USPSTF recommends annual screening for lung cancer with low-dose computed tomography in adults ages 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery".[4]

Study design

The study looked at 53,454 current or former heavy smokers from 33 medical centers in the US. The ages of the patients in the trial varied from 55 to 74. When their initial findings were published in the New England Journal of Medicine, the researchers reported that low-dose CT scanning was associated with a 20% decrease in deaths from lung cancer,[5][6] and that this effect was visible in both current smokers and former smokers.[7] More recent research based on this trial, published in JAMA Internal Medicine,[8] has found that low-dose computed tomography detects many false positives—in the study, 18% of total detections were considered to be an overdiagnosis, i.e. the cancer would never have threatened the life of the patient.[9]

The National Cancer Institute funded a $300m study, the National Lung Screening Trial (NLST), which began in 2002, to compare the effectiveness of CT scan screening versus X-ray screening.[10][11] This study, too, raised concern in the media over potential conflicts of interest related to the tobacco company, although this time on the contra-CT scan side: on October 8, 2007, the Wall Street Journal reported that at least two lead investigators of the study had conflicts of interest arising from their serving as paid, expert defense witnesses for the tobacco industry – one of them had given testimony asserting that promoting CT screening was "reckless or irresponsible", and another had provided an expert report warning that CT screening "may do more harm than good."[12]

Results

Deaths in either group were then logged for up to five years.[10] As of October 2010, 354 people in the CT scan group had died from lung cancer, versus 442 people in the X-ray group; in other words, deaths in the CT scan group of patients were 20.3% lower than in the X-ray group.[10] The study's review board concluded that this difference was statistically significant and recommended terminating the study.[10] The director of the National Cancer Institute's director, Harold Varmus, said that early analysis results appeared to indicate that CT scans detected more lung cancers, at an earlier and more treatable stage, and that CT scans could therefore reduce the number of deaths in patients at high risk of lung cancer.[10]

References
  1. National Cancer Institute (2014). "National Lung Screening Trial (NLST) Screening - Full Text View - ClinicalTrials.gov". clinicaltrials.gov. Retrieved 23 July 2014.
  2. National Lung Screening Trial
  3. Denise Aberle; Abtin, F.; Brown, K. (2013). "Computed Tomography Screening for Lung Cancer: Has It Finally Arrived? Implications of the National Lung Screening Trial". Journal of Clinical Oncology. 31 (8): 1002–1008. doi:10.1200/JCO.2012.43.3110. ISSN 0732-183X. PMC 3589698. PMID 23401434.
  4. "Lung Cancer Screening". U.S. Preventative Services Task Force. 2013. Archived from the original on 2010-11-04. Retrieved 2014-07-24.
  5. National Lung Screening Trial Research Team; Aberle, D. R.; Adams, A. M.; Berg, C. D.; Black, W. C.; Clapp, J. D.; Fagerstrom, R. M.; Gareen, I. F.; Gatsonis, C.; Marcus, P. M.; Sicks (2011). "Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening". New England Journal of Medicine. 365 (5): 395–409. doi:10.1056/NEJMoa1102873. PMC 4356534. PMID 21714641.
  6. NIH-funded study shows 20 percent reduction in lung cancer mortality with low-dose CT compared to chest X-ray
  7. Sifferlin, Alexandra (30 July 2013). "Panel Advises Annual Lung Cancer Screening for Current and Former Smokers". Time. Retrieved 20 December 2013.
  8. Patz Jr, E. F.; Pinsky, P.; Gatsonis, C.; Sicks, J. D.; Kramer, B. S.; Tammemägi, M. C.; Chiles, C.; Black, W. C.; Aberle, D. R.; for the NLST Overdiagnosis Manuscript Writing Team (2013). "Overdiagnosis in Low-Dose Computed Tomography Screening for Lung Cancer". JAMA Internal Medicine. 174 (2): 269–74. doi:10.1001/jamainternmed.2013.12738. PMC 4040004. PMID 24322569.
  9. Study Suggests Overdiagnosis in Screening for Lung Cancer With Low-Dose CT
  10. UPDATE: US Lung Cancer Screening Study Shows Benefit With CT Vs. X-Ray, by Jennifer Corbett Dooren. Published in the Wall Street Journal on November 4, 2010
  11. When It Comes to Lung Cancer, She Doesn’t Believe in Waiting by Denise Grady. Published in The New York Times on 31 October 2006
  12. Critics Question Objectivity Of Government Lung-Scan Study, by David Armstrong. Published in the Wall Street Journal on October 8, 2007

Further reading

The trial's main result is here:

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