Background: Mediastinal lymph node involvement is one of the most important prognostic factors of survival in lung cancer. We analyzed the value of flourodeoxyglucose- positron-emission tomography (FDG-PET) in mediastinal lymph node staging of non-small-cell lung cancer.

Methods: The study included 53 patients (45 men, 8 women; mean age 64 years; range 49 to 75 years) who were candidates for surgery for non-small cell lung cancer and had no distant metastasis on an FDG-PET scan. Mediastinal lymph nodes were assessed with PET and computed tomography (CT) and the results were compared in relation with histopathologic type of tumor, operations performed, lymph node dissections during thoracotomy, and histopathologic results.

Results: Compared to the CT scan, PET had a higher sensitivity (66.7% vs 36.7%), positive predictive value (51.3% vs 39.3%), and negative predictive value (90.4% vs 83.5%), but a lower specificity (83.2% vs 85%) in the evaluation of mediastinal lymph nodes. The sensitivity rates for PET and CT were found to be significantly different (p=0.004).

Conclusion: Our data suggest that lymph node involvement should be evaluated with mediastinoscopy if the standardized maximum uptake value of the PET scan is greater than 2.5, and that a direct thoracotomy would not be less appropriate if an uptake value of less than 2.5 is obtained.

Keywords : Carcinoma, non-small-cell lung/radionuclide imaging; lung neoplasms/radionuclide imaging; lymphatic metastasis; sensitivity and specificity; tomography, emission-computed