Detection of residual tumours in postchemotherapy testicular cancer by FDG-PET.

The aim of this study was to investigate whether 2-(F-18)-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) could reliably detect testicular cancer in patients following chemotherapy. Twenty FDG-PET studies were performed on 15 patients with metastatic seminoma or non-seminoma. Tracer uptake in the PET study was measured by calculating the standardised uptake value (SUV) for the tracer. Nine lesions out of 20 were judged to be positive based on high FDG uptake. Three proved to represent inflammatory changes in non-cancerous tissue. Eleven PET studies were negative. In one of these, viable tumour was found at retroperitoneal lymphadenectomy. The median SUV values of metastatic tumours and benign residual tumours were 2.7 (range 1.6-9.5, n = 10) and 1.7 (range 0.7-5.5, n = 15), respectively. The large overlap of SUVs between these groups was due to the relatively high FDG uptake in inflammatory tissue (median 4.2, range 2.0-5.5, n = 4). The results indicate that FDG imaging of metastatic testicular cancer after chemotherapy has limited value because of a potentially high accumulation of FDG in inflammatory tissues.