Positron emission tomography and histology of residual postchemotherapy masses in patients with nonseminomatous germ cell tumours
Abstract
The value of using fluorodeoxyglucose positron emission tomography (FDG-PET) before residual mass resection was studied in patients with nonseminomatous germ cell tumours (NSGCTs) after orchiectomy and platinum-based chemotherapy. Methods: Thirty patients with NSGCTs who had been investigated with FDG-PET in the preoperative period were evaluated retrospectively.
We have calculated specificity, sensitivity, positive predictive value (PPV) and negative predictive value (NPV) of FDG-PET to correctly predict the presence of viable carcinoma, mature teratoma, and necrotic/scar tissue in postchemotherapy residual masses. Results: FDG-PET was evaluated as negative, positive, or inconclusive in 11 (37%), 17 (57%) and 2 (7%) patients, respectively.
Histological examination of the resected residual masses showed immature tumour elements, mature teratoma, and no tumour structures in 12 (40%), 11 (37%), and 7 (23%) patients, respectively. FDG-PET correctly identified only 50% of lesions with immature tumour elements.
FDG-PET was negative in 13/21 (62%) patients with immature elements and/or mature teratoma - histologies that require surgical resection because of high risk of relapse. Conclusions: Sensitivity, specificity, PPV, and NPV of FDG-PET were insufficient for characterisation of postchemotherapy residual lesions in NSGCT patients.
These residual masses should be resected if technically possible regardless of the FDG-PET result.