Two patients with prostate cancer and normal PSA serum levels of 2.5 and 3.1 ng/ml at diagnosis, respectively, were included in the series by Testa et al(13), but advanced pathological stage (pT3a) and high-risk disease (Gleason score 4+3) was identified in one patient without specific information with regard to the sensitivity to choline PET imaging. Here, KLK3 is linked to prostate carcinoma.