2-¹8fluoro-deoxy-D-glucose positron emission tomography (FDG-PET) for postchemotherapy seminoma residual lesions: a retrospective validation of the SEMPET trial.

BACKGROUND: 2-¹8fluoro-deoxy-D-glucose positron emission tomography (FDG-PET) has been recommended in international guidelines in the evaluation of postchemotherapy seminoma residuals. Our trial was designed to validate these recommendations in a larger group of patients. PATIENTS AND METHODS: FDG-PET studies in patients with metastatic seminoma and residual masses after platinum-containing chemotherapy were correlated with either the histology of the resected lesion(s) or the clinical outcome. RESULTS: One hundred and seventy seven FDG-PET results were contributed. Of 127 eligible PET studies, 69% were true negative, 11% true positive, 6% false negative, and 15% false positive. We compared PET scans carried out before and after a cut-off level of 6 weeks after the end of the last chemotherapy cycle. PET sensitivity, specificity, negative predictive value (NPV), and positive predictive value were 50%, 77%, 91%, and 25%, respectively, before the cut-off and 82%, 90%, 95%, and 69% after the cut-off. PET accuracy significantly improved from 73% before to 88% after the cut-off (P=0.032). CONCLUSION: Our study confirms the high specificity, sensitivity, and NPV of FDG-PET for evaluating postchemotherapy seminoma residuals. When carried out at an adequate time point, FDG-PET remains a valuable tool for clinical decision-making in this clinical setting and spares patients unnecessary therapy.

Predictive impact of 2-18fluoro-2-deoxy-D-glucose positron emission tomography for residual postchemotherapy masses in patients with bulky seminoma.

PURPOSE: To establish the predictive potential of 2-18fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) for detecting viable tumor tissue in residual postchemotherapy masses of seminoma patients. PATIENTS AND METHODS: In this prospective multicenter trial, results of FDG PET studies in seminoma patients with postchemotherapy masses > or = 1 cm were correlated with either the histology of the resected lesion or the clinical outcome on follow-up without resection. Negative PET scans of residual lesions that were devoid of viable tumor tissue on resection or disappeared, shrunk, or remained stable in size for at least 2 years were rated as true-negative (TN). Positive scans without histologic or clinical evidence of tumor tissue were classified as false-positive. In patients with histologically positive or progressive lesions, positive PET scans were defined as true-positive (TP) and negative scans, false-negative (FN). RESULTS: Thirty-seven PET scans of 33 patients were assessable at a median follow-up time of 23 months (range, 2 to 46 months). Histologic data were available from nine patients who had undergone resection. Twenty-eight patients were followed-up clinically and radiologically. Twenty-eight scans were TN, eight were TP, and one was FN. All 14 residual lesions more than 3 cm and 22 (96%) of the 23 < or = 3 cm were correctly predicted by FDG PET. The specificity (100%; 95% confidence interval [CI], 87.7% to 100%), sensitivity (89%; 95% CI, 51.7% to 99.7%), positive predictive value (100%), and the negative predictive value (97%) of FDG PET were superior to data obtained by assessing residual tumor size (< or = or > 3 cm). CONCLUSION: FDG PET is a clinically useful predictor of viable tumor in postchemotherapy residuals of pure seminoma, especially those greater than 3 cm.

Chemotherapy for germ cell tumors relapsing after high-dose chemotherapy and stem cell support: a retrospective multicenter study of the Austrian Study Group on Urologic Oncology.

BACKGROUND: In most patients with advanced refractory germ cell tumors undergoing high-dose chemotherapy with stem cell support (HDCT) the disease progresses after HDCT. This study was designed to shed light on the unestablished role of post-HDCT chemotherapy. PATIENTS AND METHODS: In a retrospective multicenter study data of 47 evaluable patients from nine centers subjected to post-HDCT chemotherapy for progression of their germ cell tumors were collected in a questionnaire survey and analyzed for treatment response and survival. RESULTS: Of 191 patients pretreated by HDCT, 48 (25%) were subjected to post-HDCT chemotherapy for disease progression. Remission was achieved in 17 (36%) and marker-negative remission in eight (17%). The median survival time was 26 weeks, 65 weeks for responders and 13 weeks for non-responders. Only one of 47 evaluable patients achieved sustained complete remission. Remissions significantly correlated with the post-HDCT interval, the use of ifosfamide and the combination regimens of cisplatin + etoposide i.v. or ifosfamide and of paclitaxel + ifosfamide or cisplatin. On univariate analysis a longer post-HDCT interval, the use of cisplatin, paclitaxel and ifosfamide and the combined use of paclitaxel + ifosfamide and/or cisplatin significantly improved the chances of survival. On multivariate analysis only treatment with paclitaxel and ifosfamide retained independent prognostic significance for survival. CONCLUSIONS: One third of the patients considered to be candidates for further chemotherapy once progressive after HDCT went into remission with a gain in survival time. Sustained remissions may occur, but are rarely seen. Paclitaxel and ifosfamide appear to be the most effective drugs in these heavily pretreated patients.