PC is considered castrate resistant during ADT with castrate levels of serum testosterone (<50 ng/dL) if it fullfils one or more of the following criteria: 1) a rise of prostate-specific antigen (PSA) serum levels (biochemical progression), 2) development of symptoms in the presence of pre-existing cancer (clinical progression) or 3) detection of new metastatic lesions on imaging (radiographic progression) [51, 52]. This evidence concerns the gene KLK3 and cancer.