DETECTION OF EXTRATHORACIC METASTASES BY POSITRON-EMISSION-TOMOGRAPHYIN LUNG-CANCER

Background. Accurate staging of non-small cell lung cancer is essentia l for treatment planning. We evaluated in a prospective study the role of whole-body 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) positron emissio n tomography (PET) in mediastinal nodal staging with a positive predic tive value of 96%. The study was continued to further evaluate the val ue of whole-body FDG PET in detecting unexpected extrathoracic metasta ses (ETMs) in patients qualifying far surgical treatment by convention al staging. Methods. One hundred patients underwent clinical evaluatio n, chest and upper abdominal computed tomography scan, mediastinoscopy (lymph nodes greater than 1 cm on computed tomography), and routine l aboratory tests. In 94 patients with stage IIIa or less and 6 with sus pected N3 a whole-body FDG PET was performed. If clinical signs of ETM s were present additional diagnostic methods were applied, All finding s in the FDG PET were confirmed histologically or radiologically. Resu lts. Unexpected ETMs were detected in 13 (14%) of 94 patients (stage I IIa or less) at 14 sites. In addition 6 of 94 patients were restaged u p to N3 after PET. The suspected N3 disease (stage IIIb) on computed t omography was confirmed by PET in all 6 patients. There was no false p ositive finding of ETM. Weight loss was correlated with the occurrence of ETM: more than 5 kg, 5 of 13 patients (38%); more than 10 kg, 4 of 6 patients (67%). Pathologic laboratory findings were not predictive for ETM. Conclusions. Whole-body FDG PET improves detection of ETMs in patients with non-small cell lung cancer otherwise eligible for opera tion. In 14% of patients (stage IIIa or less), ETMs were detected, and in total, 20% of the patients were understaged. (Ann Thorac Surg 1998 ;66:886-93) (C) 1998 by The Society of Thoracic Surgeons.