F-18 fluorodeoxyglucose positron emission tomography in the non-invasive staging of non-small cell lung cancer

Objective: Positron emission tomography (PET) using F-18 fluorodeoxyglucose (FDG), a glucose analogue, as a metabolic tumour marker, has been proposed for the non-invasive staging of oncological disease. Tumours demonstrate i ncreased glycolytic activity and thereby, FDG PET can differentiate benign from malignant lesions. To determine its role in the mediastinal staging of patients with suspected non-small cell lung cancer, a prospective study of FDG PET and computed tomography (CT) compared to surgery and pathology was performed. The analysis group consists of 50 patients, 37 men and 13 women , mean age 64 years (range, 41-78 years). Methods: A nuclear physician, bli nd to the clinical and CT data, graded the FDG PET studies qualitatively on a five-point scale, based on the intensity of glucose uptake, for the pres ence of mediastinal nodal tumour involvement. Scores of four or greater wer e considered positive for tumour. An experienced radiologist interpreted th e patients' CT scans blind to the other data. The CT criterion for tumour i nvolvement was a nodal long axis diameter of 10 mm or greater. All patients underwent either thoracotomy or mediastinoscopy to obtain surgical specime ns. The PET, CT, surgery and pathology were mapped according to the America n Thoracic Society nodal classification resulting in 201 nodal stations eva luated. The imaging studies were analysed for N2 or N3 tumour involvement c ompared to histology or dissection of nodal stations. Results: All patients had proven non-small cell lung carcinoma. PET excluded tumour in 175 of 18 1 nodal stations (specificity 97%) compared to 162 of 181 (specificity 90%) by CT. PET correctly identified 16 of 20 (sensitivity 80%) nodal stations with tumour compared to 13 of 20 by CT (sensitivity 65%). Overall, PET corr ectly staged 191 of 201 nodal stations (accuracy 95%) compared to 175 of 20 1 by CT (accuracy 87%). By the McNemar test, PET was significantly more spe cific than CT in excluding nodal tumour involvement (chi(2) = 5.5, P < 0.05 ). Conclusions: FDG PET is more specific than computed tomography in the no n-invasive mediastinal staging of non-small cell lung cancer and has an imp ortant clinical role in the pre-operative staging of lung cancer patients. (C) 1999 Elsevier Science B.V. All rights reserved.