The role of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in the evaluation of residual germ cell tumours

Full text: The role of FDG-PET is not well established in the assessment of patients with germ cell tumours. The aim of this study was to assess the accuracy of FDG-PET in detecting residual disease in patients with germ cell tumours, and its potential role in patient management. A total of 34 FDG-PET scans in 29 patients (23 patients (IF:22M) with nonseminomatous germ cell tumours (NSGCT), and 6 male patients with advanced seminoma) performed over a 4 yr period were evaluated. Results of FDG-PET studies were compared to pathology or follow-up. For NSGCT patients, pathological evidence of residual high grade tumour was seen in 9 patients on subsequent surgical specimens. FDG-PET studies were true positive in all of these patients. In 8 NSGCT patients pathology revealed fibrosis or teratoma at subsequent surgery: all had negative FDG-PET studies. There were no false positive, nor false negative FDG-PET studies. Resection was not performed in the remaining 6 patients, and on follow-up 2 patients had a progressive clinical course after positive FDG-PET scans, and 2 patients were in clinical remission 3 and 29 months after a negative FDG-PET study, respectively. Two patients were not evaluable. Of the 6 seminoma patients, 5 underwent further chemotherapy /radiotherapy after having abnormal FDG-PET studies due to clinical evidence of disease. The 6th pt with a negative FDG-PET study had stable retroperitoneal lymph node enlargement after 3 years follow-up. In our series FDG-PET was able to predict the presence of high grade malignancy within residual masses in patients with NSGCT and seminoma with a high accuracy. These initial results encourage further evaluation