KLK3 and prostate cancer: Studies in patients with metastatic prostate cancer have shown that flares peak on bone scintigraphy 6 to 8 weeks after treatment22,23, and as a result of this, the Prostate Cancer Working Group 2 (PCWG2) do not recommend any immediate changes to treatment if there is an increase in bone accumulation using scintigraphy, or an increase in PSA levels within 12 weeks of treatment initiation24.