Conclusions: The almost complete suppression of the tumor stimulator FSH using ADT plus E4 observed in all individual patients in this study, along with the augmented suppression of IGF-1 versus an increase by ADT only, may be clinically relevant and suggest the enhanced anti-cancer treatment efficacy of E4 in addition to the previously reported additional suppression of total and free T and PSA. Here, KLK3 is linked to cancer.