Efficacy of low-dose computed tomography screening for lung cancer: the current state of evidence of mortality reduction.

The interim and final results of randomized controlled trials on the efficacy of lung cancer computed tomography (CT) screening have been reported recently from Western countries. The outcome of the National Lung Screening Trial (NLST) demonstrated the efficacy of low-dose thoracic CT screening for heavy smokers; however, other studies have found no apparent reduction in the mortality rate, and the outcome of the NELSON study is awaited. To date, a few studies have reported on the efficacy of lung cancer CT screening for non-/light smokers. A report from the Hitachi district, which is an ecological/time series study where non-/light smokers account for approximately half of the CT screening examinees, was published in 2012, with an outcome suggesting efficacy. Currently, a randomized controlled trial (JECS Study) is underway in Japan with non-/light smokers as the subjects, and this trial is very important in terms of cancer prevention.