[Role and limits of diagnostic imaging in the staging of lung cancer]

A total of 474 histologically proved Lung Cancers (LC) were evaluated by Conventional Radiology (CR) and Computed Tomography (CT) in order to assess the role of these two diagnostic modalities in the staging of LC. In 196/474 LC it was possible also to refer, for the evaluation of the diagnostic reliability, to the surgical control. The CR features of LC both at stage III (13% of the global series) and at stage I-peripheral T1 (16% of the global series) presented very high positive and negative predictive values (90% and 95%, retrospectively); in these cases it was considered useless to perform CT. The CT grading showed a high negative predictive value in excluding stage III caused respectively by grade T3 (91.5%) and grade N2 (93.5%). As to the staging, the CT assessment of the stage I and II showed a high predictive value (91.5%). On the other hand, the CT assessment of stage III presented an unsatisfactory predictive value (71%), due to the low predictive value in grade T3 (71.5%), poor in grade N2 (57.5%). The increase of the value threshold mediastinal adenopathies from 1 to 2 cm, leads to a great improvement of this predictive value (92%). The CT reliability was matched with the two different surgical "philosophies" (non aggressive or aggressive); surgery was excluded or performed according to the presence of omo-lateral mediastinal adenopathy. A correct advice to perform surgery was achieved in 33.5% (non aggressive "philosophy") and 43.8% (aggressive "philosophy") of cases; surgery was correctly excluded respectively in 49.6% and 45.9%. The resort to mediastinoscopy was advised in 7.8% and 1.3% of the cases respectively. In both "philosophies" the error of under-staging was lower (2.5%), than that of over-staging (6.6%).