In a recent issue of Cancer Biology & Therapy, Vitale et al. introduced the paper of Franco et al. reporting the expression of GPER (a seven-transmembrane-spanning receptor also known as GPR30) on testicular germ cell tumors (TGCTs). The paper commented on the possible pathophysiological role of this G-protein-coupled receptor (GPCR) during testicular germ cell carcinogenesis. They also proposed the potential use of selective antagonists of GPER as new-targeted therapy in these tumors. We agree with this hypothesis and would like to highlight here some published results supporting this hypothesis and give some details concerning the role of estrogens and xeno-estrogens in testicular carcinogenesis and the effects of GPER antagonist in human seminoma cells. We are sure that this information we obtained by working for several years on a human seminoma cell line will be appreciated by the readers of Cancer Biology & Therapy.