Open questions to be addressed in the future

The standardization of diagnostic assessment, risk stratification and therapy as well as participation in international registries will advance the knowledge of the biology and the clinical behaviour of SCSTs. However, due to rarity and heterogeneity of these tumors, randomized therapeutic studies will be impossible, even at the international level. Thus, research will have to focus on biological studies that may reveal the genetic basis of tumor development and risk constellations within tumor predisposition syndromes. Moreover, for testicular SCSTs, the evaluation of surgical data may address whether testis sparing may be feasible and safe. In contrast, the focus in OSCSTs will remain in the optimal risk stratification in tumors with high-risk histology and stage IC tumors. Last, effective salvage strategies must be developed in the context of the growing genetic and biological data on the rare cases of recurrent ovarian SCSTs, which have a very unfavourable prognosis.