Between the years1995 and 2004, 1,252 cases of CaP were diagnosed; 810 in the screening arm and 442 in the control arm. Men randomized to active screening had a 1.83-fold increased risk of being diagnosed with CaP compared to men in the control group. Most screened men had localized disease. The number of participants with metastatic CaP at the time of diagnosis (or with a PSA >100ng/ml) was 24 in the screening group compared to 47 in the control group (p=0.0084). This represents a 49% reduction in the risk of being diagnosed with metastatic CaP by screening over a 10-year period.
The study minimized selection bias as men were randomized without any prior information. A study limitation is that men had only sextant biopsy, although the biopsies were directly laterally.
There are studies being done in Europe currently to see the effect on prostate cancer screening. This one shows that advanced prostate cancer was much less likely to be found in screened patients.
The biopsies that were done (6) were less than are currently being done (at least 10) and patients were only screened every other year. Both of these things should lead to a further reduction in advanced cancer. I believe we are overtreating some patients, but I think we are definitely helping many people with vigilant screening.