[Positron emission tomography in germ cell tumors in men : Possibilities and limitations].

Abstract

BACKGROUND\nConventional radiographic imaging may fail to safely distinguish clinical stage\xa0I from stage IIA germ cell cancer, to localize isolated tumor marker relapses, and to equivocally identify the viability of postchemotherapy residual masses.\n\n\nOBJECTIVES\nTo provide an overview of the diagnostic value and limitations of functional imaging by positron emission tomography with 2‑deoxy-2-[fluorine-18]fluoro-D-glucose with computed tomography (18F-FDG-PET-CT) in male germ cell cancer.\n\n\nMATERIALS AND METHODS\nA\xa0narrative review based on a\xa0literature search of PubMed/MEDLINE for original articles published from 1990-2018 and conference proceedings of ASCO (American Society of Clinical Oncology) and EAU (European Association of Urology) annual meetings 2014-2017 is presented.\n\n\nRESULTS\n18F-FDG-PET-CT does not improve diagnostic accuracy compared to conventional CT imaging clinical stage (CS)\xa0I disease. Particularly PET-negativity of postchemotherapy residual masses of seminomas >3\u202fcm in size guide decision-making against further additional treatment. Even PET-positive residues must not result in relapse. For nonseminoma, the value of PET imaging is reduced by potential mature teratoma components, which are commonly PET negative.\n\n\nCONCLUSIONS\nCurrent guidelines recommend 18F-FDG-PET-CT 6-8\xa0weeks postchemotherapy for viability assessment of seminoma residues >3\u202fcm in size. Exceptional circumstances, in which 18F-FDG-PET-CT may be helpful, include: (1)\xa0detection of active disease in CS IS, (2)\xa0viability assessment of residual masses >1\u202fcm where complete secondary resection is impossible, (3)\xa0staging at marker relapse with unconspicuous conventional CT scan, (4)\xa0early response assessment during chemotherapy.