Does positron emission tomography using 18-fluoro-2-deoxyglucose improve clinical staging of testicular cancer? - Results of a study in 50 patients

Objectives. To compare positron emission tomography (PET) using 18-fluoro-2 -deoxyglucose (FDG) with conventional clinical staging in unselected patien ts with germ cell cancer. Methods. Fifty patients underwent PET scans of the abdomen (n = 50) and che st (n = 41) after the initial diagnosis. PET images were evaluated qualitat ively and quantitatively using standardized uptake values (SUVs). The resul ts were compared with computed tomography (CT) results and tumor markers (h uman chorionic gonadotropin, alpha-fetoprotein, and lactate dehydrogenase). Retroperitoneal lymphadenectomy in 12 patients and clinical staging, inclu ding follow-up data in all patients, were taken as a reference standard. Results. PET detected metastases in 13 (87%) of 15 patients and excluded me tastases in 33 (94%) of 35 patients. A sensitivity of 73% and a specificity of 94% were obtained using CT. The respective values for tumor marker dete rmination were 67% and 100%. Retroperitoneal metastases were detected in 2 patients by PET only and in 1 patient by CT only. In the latter patient, su rgery of a residual mass after chemotherapy revealed a well-differentiated teratoma. False-negative findings with PET and CT occurred in 2 patients wi th retroperitoneal metastases approximately 10 mm in size. False-positive f indings were due to sarcoidosis or to muscular activity of the neck. Quanti tative FDG uptake was very heterogeneous, with an SUV ranging from 1.8 to 1 7.3. Conclusions. FDG PET has the potential to improve clinical staging of testi cular cancer. However, PET, as well as CT, is limited in the detection of s mall retroperitoneal lymph node metastases. UROLOGY 54: 900-904, 1999. (C) 1999, Elsevier Science Inc.