KLK3 and neoplasm: Importantly, every case of prostate adenocarcinoma also contains a minor component of NE cells that are negative for AR and PSA.13,14 Because NE cells are AR negative and androgen-independent, they are spared by hormonal therapy and subsequently, enriched in the tumor.15,16 Furthermore, 17%–30% of recurrent castration-resistant tumors display a variant histology known as small cell neuroendocrine carcinoma (SCNC)17,18 with the tumor composed entirely of NE cells.