Journal of Clinical Oncology, 2006 ASCO Annual Meeting Proceedings (Post-Meeting Edition).
Vol 24, No 18S (June 20 Supplement), 2006: 4521
© 2006 American Society of Clinical Oncology

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Abstract

[18F]-FDG-PET in germ cell tumors following chemotherapy: Results of the German multicenter trial

UK Eppendorf, Hamburg, Germany; Military Hospital, Hamburg, Germany; Urban Hospital, Berlin, Germany; Charité, Berlin, Germany; University Hospital, Muenster, Germany; University Hospital, Essen, Germany; University Hospital, Tübingen, Germany

4521

Background: The aim of this study was to evaluate the viability of residual masses following chemotherapy in patients (pts) with germ cell cancer (GCT) using FDG-PET. Methods: Pts with diagnosis of GCT at primary diagnosis or at relapse were included if residual masses (> 1 cm) were present following chemotherapy. 140 pts, 27 with primary extragonadal GCT, aged 15.7–59.2 (mean age: 32.7 years) treated in 18 centers were examined with concurrent FDG-PET and CT. FDG-PET was performed in fasting state. Images were reconstructed by filtered back projection. All PET-scanners were calibrated using the same phantom. The presented data are based on visual scan analysis. All pts underwent surgery for residual masses. Thus, all results were validated by histology. Results: Histology of the primary tumor included 20 seminoma and 109 NSGCT, while 11 pts had no primary histology. 88 pts (63%) had no persistent GCT. 120 pts (86%) demonstrated residual masses in retroperitoneal lymph nodes; in 56 pts (40%) residual masses were localized in the thorax and in 8 pts elsewhere (multiples possible). 40 pts (29%) presented active residual carcinoma and 54 (39%) presented residual teratoma (combination possible) following chemotherapy. Correct classification of the residual mass by FDG-PET was achieved in 79 of 140 (56%), while CT scans were correct in 58 of 140 pts (42%). 46 of 89 patients with a positive FDG-PET turned out to have viable tumor while in 36 out of 52 patients with a negative scan no lymph node metastases were found. FDG-PET turned out to show a sensitivity of 73% and specificity of 44%. Positive and negative predictive value (PPV, NPV) were 48% and 69% and accuracy 56%, respectively. In NSGCT 58 pts had no active tumor and 28 were true negative with FDG-PET resulting in a specificity of 47% and a NPV of 67%. 36 patients were true positive with a PPV of 54% and a sensitivity of 72%. Conclusion: FDG-PET for GCT following chemotherapy has a higher accuracy than CT, but sensitiviy is still too low to avoid subsequent resections in patients with NSGCT.

Abstract presentation from the 2006 ASCO Annual Meeting