Impact of [¹⁸F]FDG-PET on the primary staging of small-cell lung cancer

The purpose of this study was to evaluate the impact of [¹⁸F]fluorodeoxy-d-glucose positron emission tomography (FDG-PET) on the primary staging of patients with small-cell lung cancer (SCLC).

FDG-PET was performed in 120 consecutive patients with SCLC during primary staging. In addition, brain examinations with both FDG-PET and cranial magnetic resonance imaging (MRI) or computed tomography (CT) were performed in 91 patients. Results of FDG-PET were compared with those of conventional staging procedures. FDG-PET detected markedly increased FDG uptake in the primary tumours of all 120 patients (sensitivity 100%).

Complete agreement between FDG-PET results and other staging procedures was observed in 75 patients. Differences occurred in 45 patients at 65 sites. In 47 sites the FDG-PET results were proven to be correct, and in ten, incorrect. In the remaining eight sites, the discrepancies could not be clarified. In 14/120 patients, FDG-PET caused a stage migration, correctly upstaging ten patients to extensive disease and downstaging three patients by not confirming metastases of the adrenal glands suspected on the basis of CT. Only 1/120 patients was incorrectly staged by FDG-PET, owing to failure to detect brain metastases. In all cases the stage migration led to a significant change in the treatment protocol. Sensitivity of FDG-PET was significantly superior to that of CT in the detection of extrathoracic lymph node involvement (100% vs 70%, specificity 98% vs 94%) and distant metastases except to the brain (98% vs 83%, specificity 92% vs 79%). However, FDG-PET was significantly less sensitive than cranial MRI/CT in the detection of brain metastases (46% vs 100%, specificity 97% vs 100%).

The introduction of FDG-PET in the diagnostic evaluation of SCLC will improve the staging results and affect patient management, and may reduce the number of tests and invasive procedures.