Early cryotherapy experience made it clear that specific thresholds may be meaningless due to PSA production by residual tissue surrounding the urethra or in a benign median lobe, and the fact that a PSA of 0.4 is expected when 1 g of prostate tissue has been preserved in men free of prostate cancer.[14] It is intended that the data set collected with the COLD registry will be used to create a scientifically based definition of biochemical failure that is specific to primary prostate cancer cryoablation as these data accumulate and mature. The gene discussed is KLK3; the disease is prostate carcinoma.