Evaluation of N parameter in the staging of non-small cell lung cancer: role of CT and PET.

PURPOSE: To determine diagnostic accuracy of CT and FDG-PET for the evaluation of N status in non-small cell lung cancer. MATERIALS AND METHODS: Thirty-eight CT scans and PET scans of patients with non small-cell lung cancer were retrospectively reviewed. The data of the noninvasive techniques about N status were compared with the pathology findings obtained by standard lymphadenectomy. RESULTS: The CT results were concordant with surgery in 24 out of 38 cases (63\%); in discordant cases CT understaged 8 patients and overstaged 6. The PET images were concordant with surgery in 29 cases (76\%); of the remaining 9, PET understaged 5 cases and overstaged 4. Concerning the N parameter, CT had a sensitivity of 42.8\% and a specificity of 83.3\%, while PET had a sensitivity of 71.4\% and a specificity of 91.6\%. CONCLUSIONS: In our experience the diagnostic accuracy of PET is superior to that of CT, in agreement with the most important studies in the literature. On only one occasion did PET fail to differentiate between hilar uptake (N1) and the central primary tumour, an area in which CT provided more precise anatomic details. Nonetheless, we believe that PET should be performed in all patients affected by lung cancer, with the only exception of patients shown to be not suitable for surgery after CT examination.