CTC enumeration has been found to correlate well with progression free survival (PFS) and overall survival (OS) in prostate cancer patients (Armstrong et al., 2012; Diamond et al., 2012; Miyamoto et al., 2014; Pantel et al., 2019), and has been reported to outperform the traditional prostate cancer monitoring approach using serum PSA (De Bono et al., 2008). Here, KLK3 is linked to prostate carcinoma.