Computerized tomography screening for lung cancer: new findings and diagnostic work-up.

On computerized tomography (CT) screening for lung cancer within the Early Lung Cancer Action Project, both at baseline and repeat screening, we found not only solid but also subsolid nodules, which unlike solid ones do not completely obscure the lung parenchyma. We established that subsolid nodules represent approximately 20% of the nodules shown on screening and that they have a higher frequency of malignancy than solid nodules. Although we found growth of solid nodules to be a reliable indicator of malignancy, growth of subsolid nodules was more difficult to assess. On review of our results to date in screening, we have continued to refine our definition of a positive result of screening from that given in our initial publication on screening. We have also provided an updated screening regimen. It starts with the initial, low-dose CT test and for all those with positive results on this initial test, the regimen continues by specifying the work-up needed to rule-in a diagnosis of malignancy. In this regimen, we found growth assessed by high-resolution CT to be a useful indicator of malignancy and have developed image-processing tools to help in this assessment. Once growth is ascertained, we recommend fine-needle aspiration for confirmation of malignancy. It may be that once criteria for definitive growth are established and validated, fine-needle aspiration may become optional. However, in the meantime, in the context of screening, a more cautious approach is warranted.