"The incidence peaks in the 3rd-4th decades of life for seminomas and in the 2nd-3rd decades for non-seminomatous tumours, with significant variation by histological type 4,8. In the USA, the highest incidence occurs in Hispanic and non-Hispanic white populations 7."
"history of viral infections, e.g. HPV, HIV (predominantly associated with non-seminomatous tumours) 5"