ASCO 2006 - GU Oral Presentation: Testicular Cancer
March 16, 2017
UroToday - Three abstracts were presented at this session with the focus on imaging in the management of testicular germ cell tumors.
One option for patients with clinical stage I non-seminomatous germ cell tumors is careful observation. There is no universal consensus of the exact surveillance regimen that should be used. Mead et al. presented the results of Medical Research Council TE08. This was a prospective randomized trial comparing 2 CT scans versus 5 CT scans in patients with clinical stage I NSGCT. Four hundred fourteen patients were randomized to chest and abdominal CT scans at 3 and 12 months versus 3, 6, 9, 12, 24 months. The primary endpoint of this trial was the proportion of patients in each group that were found to have intermediate or poor prognosis germ cell tumor using the International Classification. 247 patients were randomized to 2 CT scans and 167 patients to 5 CT scans. 37 of 247 (15%) patients in the 2 CT scan group ultimately relapsed, compared to 33 of 167 (20%) in the 5 CT scan group. Three patients relapsed with intermediate risk disease (based upon level of LDH), 2 in the 2 CT scan arm and 1 in the 5 CT scan arm for a difference of 0.2% (90% CI -1.2 - 1.6%). No deaths were reported in this trial. The authors concluded that the schedule of 2 CT scans should be considered a "new standard". It is important to note that the National Comprehensive Cancer Network Clinical Practice Guidelines for Testicular Cancer recommend a surveillance schedule that has substantially more frequent CT scans.
Two abstracts examined the role of FDG-positron emission tomography (PET) in the management of germ cell tumors. Huddart, et al. presented the results of MRC study TE22 in which patients with high risk clinical stage I NSGCT underwent FDG-PET imaging. Patients with positive scans received 2 cycles of BEP. Those with negative scans were observed. The primary outcome of this study was the negative predictive value of FDG-PET. Between May 2002 and January 2005, 116 patients were registered; 111 underwent FDG-PET scans. The study was stopped early because of an unacceptably high rate of relapse in the FDG-PET negative patients. With a median follow-up of 11 months, 33 of 87 patients on surveillance relapsed for a one-year relapse free rate of 63% (90% CI 54 - 72%). The authors concluded that FDG-PET did not have a high enough negative predictive value to be used in this setting.
The management of the post-chemotherapy residual mass in patients with NSGCT is surgical resection. No imaging modality can predict necrosis with enough accuracy to avoid surgery. De Wit, et al. presented a study which examined the role of FDG-PET in predicting necrosis in the post-chemotherapy residual mass. In this study, 140 patients with metastatic germ cell tumor underwent FDG-PET after completion of chemotherapy. Correct classification of the residual mass was achieved in 79 of 140 patients for an accuracy of 56%. The authors concluded that FDG-PET can not predict post-chemotherapy histology accurately enough to avoid surgery. This confirms work of prior investigations.
By David Vaughn, MD
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