Is Positron Emission Tomography Reliable to PredictPost-Chemotherapy Retroperitoneal Lymph NodeInvolvement in Advanced Germ Cell Tumors of theTestis?

PURPOSE: To evaluate if 18 fluorodeoxyglucose positron emission tomography(18FDG-PET) scan could identify post-chemotherapy retroperitoneal lymphnode (RPLN) involvement in advanced germ cell tumors of the testis.MATERIALS AND METHODS: Between January 2005 and January 2009, 16patients with advanced germ cell tumors of the testis underwent RPLNdissection (RPLND) following chemotherapy. Before RPLND, abdominalcomputed tomography (CT), magnetic resonance imaging (MRI), and18FDG-PET were performed in all the patients. Findings on 18FDG-PETwere compared with pathological evaluation of the removed lymphatic tissue.RESULTS: Both abdominal CT and MRI demonstrated retroperitonealmasses in all the patients following chemotherapy. Although PET did not demonstrate any activity in 8 patients, tumor was detected histopathologically.In 1 patient, 18FDG-PET demonstrated activity; however, no tumor wasdetected on pathology. Of the remaining 7 patients, 18FDG-PET findingswere concordant with the histopathological findings. No activity wasdetected in 2 patients with no tumors whereas all 5 patients harboring viabletumor cells showed positive 18FDG-PET activity. In our study, sensitivityand specificity of 18FDG-PET in detecting RPLN involvement were detectedto be 39% and 67%, respectively.CONCLUSION: 18FDG-PET imaging does not seem to be a reliable methodin detecting RPLN involvement in advanced germ cell tumors of the testis following chemotherapy. Therefore, we neither recommend routine use of18FDG-PET scanning nor decide the treatment work-up by solely relying onthe 18FDG-PET findings in this patient group.