Use of Positron Emission Tomography in Assessing Hidden Extrathoracic Metastasis in Non Small Cell Lung Cancer

Positron emission tomography combined with computed axial tomography (PET/CT) is used for staging non small cell lung cancer (NSCLC). This study aims to describe PET/CT findings of unsuspected extrathoracic metastasis when used in mediastinal evaluation of patients with apparently resectable NSCLC.Prospective and concurrent study including all NSCLC patients between June 2004 and November 2006 who underwent PET/CT after considering them as candidates for surgery, with resectable disease after bronchoscopy, thorax and abdominal CT, brain CT and bone gammagraphy evaluation, if metastasis at these locations were suspected. Metastasis were confirmed histopathologically or assumed when they had a compatible evolution.A total of 91 patients with NSCLC underwent PET/CT. In 24 of them (26%) at least one suspicious extrathoracic uptake was seen. In 7 patients (7.7%) those uptakes were NSCLC extrathoracic metastasis hidden from conventional staging. In 3 of these cases (13.1%) extrathoracic uptakes corresponded to metacrhonous tumours or pre-malignant conditions. Benign lesions were found in 12 patients (13.1%), and in 2 cases (2.2%) the uptake origins were undetermined.PET/CT is a complementary diagnosis method for assessing hidden metastases which could modify the therapeutical approach in patients otherwise suitable for surgery.