The majority of untreated primary PCa present as adenocarcinomas with a luminal‐like phenotype, whereas a small subset (1%–5%) is classified as undifferentiated or anaplastic PCa variants known as small cell PCa (SCPC) or neuroendocrine PCa (NEPC), which are generally AR‐negative, have a clinically aggressive behavior and are significantly increased (up to 25%) during castration‐resistant PCa (CRPC) progression [31]. This evidence concerns the gene AR and adenocarcinoma.