The largest study to date investigating a single invitation to a PSA blood test to screen for prostate cancer has found it had a small impact on reducing deaths, but also led to overdiagnosis and missed early detection of some aggressive cancers. The CAP trial, published in the Journal of the American Medical Association (JAMA) and carried out by researchers from the universities of Bristol, Oxford and Cambridge, involved over 400,000 men aged 50-69. Just under half received a single invitation for a PSA test as part of the trial. After following up for 15 years, there was a small...