18F-fluoro-2-deoxyglucose-positron emission tomography in the evaluation of nonseminomatous germ cell tumours at relapse.

OBJECTIVES: To compare the performance of 18F-fluoro-2-deoxyglucose-positron emission tomography (FDG-PET) and computed tomography (CT) in the follow-up of nonseminomatous germ cell tumours (NSGCT) in the retroperitoneum.

PATIENTS AND METHODS: FDG-PET was used 25 times in 15 patients diagnosed with NSGCT. At the time of diagnosis five patients each were in stage I, II and III. Five patients had pure embryonal carcinoma, two had yolk sac tumours, one choriocarcinoma and seven had mixed tumours.

RESULTS: Eleven patients either presented with retroperitoneal disease or this did not disappear after chemotherapy. The results of both examinations coincided in 18 cases and were contradictory in the other seven, the difference being statistically significant (P=0.042).

CONCLUSION: In these patients FDG-PET detected the retroperitoneal relapse of NSGCT, in advanced stages treated with surgery plus chemotherapy, earlier than did CT; it also detected the presence of mature teratoma in residual retroperitoneal masses more accurately than CT. More extensive trials are needed before making conclusions about FDG-PET imaging as a routine method for NSGCT.