Lung cancer screening prevented very few lung cancer deaths among persons at lowest risk for lung cancer mortality, a new analysis of data from the National Cancer Institute’s (NCI’s) National Lung Screening Trial (NLST) has demonstrated. This information provides support for risk-based targeting of smokers for such screening.

In results reported in June 2011, the NLST showed that screening with low-dose computed tomography (LDCT) resulted in a 20% reduction in lung-cancer mortality among persons aged 55 to 74 years who had a minimum of 30 pack-years of smoking and who had quit no more than 15 years ago. However, noted the NCI’s Stephanie A. Kovalchik, PhD, and colleagues recently in The New England Journal of Medicine (2013;369:245-254), it is not known whether the benefits and potential harm of such screening vary according to lung cancer risk.

Kovalchik’s team compared findings from 26,604 NLST participants who underwent LDCT and 26,554 who underwent chest radiography, according to the quintile of 5-year risk for lung cancer mortality. This risk ranged from 0.15% to 0.55% in the lowest-risk group (quintile 1) to more than 2.00% in the highest-risk group (quintile 5).

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The researchers discovered that, compared with the radiography group, the number of lung cancer deaths per 10,000 person-years that had been prevented in the LDCT group increased according to quintile:

  • 0.2 in quintile 1
  • 3.5 in quintile 2
  • 5.1 in quintile 3
  • 11.0 in quintile 4
  • 12.0 in quintile 5

Far more false-positive results were seen in quintile 1 (1,648) than in quintile 5 (65). False-positive findings consistently decreased as lung cancer risk quintile increased (181 in quintile 2, 147 in quintile 3, and 64 in quintile 4). 

The 20% of persons at lowest risk (quintile 1) for lung cancer death accounted for only 1% of lung cancer deaths prevented by screening. In contrast, the 60% of persons at highest risk (quintiles 3 through 5) accounted for 88% of such screening-prevented deaths.