KLK3 and cancer: Over the past decades, there have been large increases in the diagnosis of prostate cancer with the widespread use of prostate-specific antigen (PSA) testing.1, 4 Small reductions in prostate cancer mortality (eg, decrease of 19 per 100 000 men in Australia from the peak in mid 1990s5) suggest this has translated into some benefit, possibly due to earlier treatment of detected aggressive cancers.5