Misuse of tumor marker levels leads to an insufficient International Germ Cell Consensus Classification (IGCCCG) risk group assignment and impaired treatment oleh Matthäus Majewski, Pia Paffenholz, Christian Ruf, Yue Che, Christoph Seidel, Julia Heinzelbecker, Hans‐Ulrich Schmelz, Cord Matthies, Peter Albers, Carsten Bokemeyer, Axel Heidenreich, Martin Pichler, Tim Nestler, the GTCSG (German Testicular Cancer Study Group)