HSD17B3 and seminoma: Except for the CYP17A1 transcript which was present at moderately higher levels in seminoma and HSD17B3 expressed at comparable levels in both histological types, the steroid hormone-related genes were upregulated in NSGCT (Fig. 7, Supplementary Table S3), in line with the generally higher serum T and E2 in NSGCT of our retrospective TGCT collective (Figs. 2, 3).