MicroRNAs in testicular cancer: implications for pathogenesis, diagnosis, prognosis and therapy.

Testicular germ cell tumors (TGCTs) represent the most common type of solid tumors among men aged 15 to 40 years. An increasing incidence has been recorded in developed countries. In clinical practice, TGCTs are classified as seminomas and non-seminomatous tumors. Non-seminomatous tumors often contain multiple different cell types and can be further sub-divided according to the histological and cellular phenotype in embryonal carcinomas, choriocarcinomas, yolk sac tumors and teratomas. For the clinical management of TGCTs, blood-based markers such as lactate dehydrogenase, alpha-fetoprotein and human chorionic gonadotropin are essential tools for diagnosis, risk assessment and patient's prognosis. However, only 60% of patients with TGCTs show increased serum levels of these tumor markers. This proportion of patients is even lower for those with seminomas or pure embryonal carcinomas as alpha-fetoprotein is predominantly related to yolk sac tumor and human chorionic gonadotropin to choriocarcinoma.