CT screening for lung cancer: update 2005

Currently available results on CT screening for lung cancer show that (1) the work-up on baseline screening can be confined to less than 15% of the individuals and to less than 6% on annual repeat screening, (2) almost all cases are detected by screening with very few diagnoses made between screening on the prompting of symptoms, and (3) over 80% of all the diagnoses are of stage I. This diagnostic performance results from following the I-ELCAP regimen of screening which defines a positive result of the initial CT in the regimen as well as the work-up leading to a diagnosis of lung cancer. The diagnostic performance raises prognostic questions as to the genuineness and curability of these screen-diagnosed lung cancers. All diagnoses of malignancy were confirmed by an expert pathology review and found to represent genuine lung cancer as defined by the 2004 World Health Organization pathologic criteria. Estimates based on growth rates suggest that about 90% of the baseline-diagnosed stage I cancers are genuine cancers, as are essentially all of those diagnosed on annual repeat screening. Preliminary results of the curability of genuine screen-diagnosed stage I lung cancers indicate a high curability rate of more than 90%. This suggests that more than a high proportion of deaths from lung cancer can be prevented by CT screening followed by early resection. Using these results, the benefit of a single round of CT screening can be determined for an individual based on the age and smoking history.