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

Abstract

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. 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. 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. 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.