• high risk;
  • low-dose computed tomography;
  • noncalcified nodules;
  • overdiagnosis bias;
  • screening;
  • smokers


While low-dose CT scans have been shown to detect greater numbers of early lung cancers than conventional CXR, the first randomized trial of CT versus CXR screening in more than 50 000 subjects has shown a 20% reduction in mortality with CT. There are several other randomized trials in progress. CT scanning may be a useful technique for identifying lung cancer at an earlier stage and may reduce mortality. However, before it can be used on a wider scale, issues such as overdiagnosis bias, cost-effectiveness, false positive findings of multiple noncalcified nodules and the willingness of the relevant population to accept CT scanning need to be evaluated. There is still very little information on the cost per life-year saved as a result of CT scanning, as the data to date is very imprecise. There is no evidence that screening programs influence smoking rates despite the inclusion of cessation programs in many trials. Furthermore, if CT screening is adopted, much work is needed to persuade individuals at high risk, mostly current or former heavy smokers with some airflow obstruction, to participate in a screening program.