Emerging data indicates that prostate tumor cells are capable of synthesizing their own androgens to sustain growth [44]: for instance, the expression of enzymes involved in de novo steroid synthesis has been reported to be up-regulated in both (metastatic) prostate tumors [34] and CRPC patients after CYP17A1 inhibitor treatment [40]. This evidence concerns the gene CYP17A1 and prostate neoplasm.