Positron emission tomography evaluation of residual radiographic abnormalities in postchemotherapy germ cell tumor patients

Purpose: This study was performed to assess the ability of positron emission tomography (PET) to differentiate residual radiographic abnormalities in postchemotherapy nonseminomatous germ cell tumor (GCT) patients. Materials and Methods: Thirty patients with nonseminomatous GCT were evaluated with PET scans before surgical resection of a residual mass or masses, Standardized uptake values (SUV) were calculated for the region of maximal 2-fluoro-2-deoxyglucose (FDG) uptake and compared with histologic findings. Results: Eleven patients had necrosis/fibrosis in the resected specimen, 15 had teratoma, and four viable GCT, The median SUV for the necrosis/fibrosis group was 2.86, teratoma 3.07, and viable GCT 8.81. A significant association between SUV and histology was found when comparing viable GCT versus necrosis/fibrosis plus teratoma (P = .004). Patients with an SUV greater than 5 were 75 times more likely to have viable cancer than teratoma or necrosis/fibrosis (odds ratio; 95% confidence interval, 3.66 to 1,536), PET did not differentiate necrosis/fibrosis from teratoma, However, PET was able to differentiate viable GCT from residual necrosis/fibrosis or teratoma. Conclusion: PET-FDG imaging can be useful for detection of residual viable carcinoma following chemotherapy in nonseminomatous GCT patients with residual masses, It may be a valuable adjunct in the determination of which patients should undergo postchemotherapy resection. (C) 1996 by American Society of Clinical Oncology.