In 46 of 84 patients fulfilling generally accepted criteria of recurrent or residual prostate cancer (5, 16, 17) and categorized as EAU Low-Risk BCR (n=7), EAU High-Risk BCR (n=18), BCR unassigned (n=10) and PSA persistence (n=11), no suspicious lesions were found. This evidence concerns the gene KLK3 and prostate cancer.