Early studies of CTC using prostate specific antigen (PSA)-specific [39] and alpha-fetoprotein (AFP)-specific [44] transcripts as markers in RT-PCR based assays have shown that non-tumor epithelial cells circulate in blood, for instance in patients with prostatitis [39] and in patients undergoing surgical procedures [44]. The gene discussed is KLK3; the disease is urogenital neoplasm.