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Cluster Randomised Trial of PSA Testing for Prostate Cancer (CAP)

The following people are involved with this project:

More about this project

Contact corresponding author Richard M. Martin, PhD:

The full study is available.

Press release: Bristol scientists behind the largest trial ever to investigate prostate cancer screening.

CAP trial videos

Does single PSA test have effect on prostate cancer detection, death?

Bottom line: A screening program that invited men to a clinic to undergo a single prostate-specific antigen (PSA) test increased detection of low-risk prostate cancer but made no significant difference in prostate cancer deaths after 10 years.

Why the research is interesting

Prostate cancer screening remains controversial because potential benefits may be outweighed by harms from overdetection and overtreatment. Current policy in the United Kingdom, where this clinical trial was conducted, doesn't advocate screening.

Who and when

419,582 men from 573 primary care practices in the United Kingdom; recruitment started in 2001 and patient follow-up ended in March 2016

Interventions and measures

189,386 men at 271 practices were invited to attend a PSA testing clinic and to receive a single PSA test while 219,439 men at 302 practices were unscreened in a control group for comparison (intervention); death from prostate cancer after about 10 years and secondary outcomes including cancer stage at diagnosis (outcomes)

How (Study Design)

This was a randomised clinical trial. RCTs allow for the strongest inferences to be made about the true effect of an intervention. However, not all RCT results can be replicated in real-world settings because patient characteristics or other variables may differ from those that were studied in the RCT.


Richard M. Martin, Ph.D., University of Bristol, England, and coauthors


PROPORTION DIAGNOSED WITH PROSTATE CANCER: Received PSA Screening (189,386 men) - 4.3%, Did Not Receive PSA Screening (219,439 men) - 3.6%
DIED OF PROSTATE CANCER: Received PSA Screening - 549 men (0.30 per 1,000 person-years), Did Not Receive PSA Screening - 647 men (0.31 per 1,000 person-years)

Study limitations

A single PSA screening may fail to reflect a long-term effect of multiple PSA testing rounds; a follow-up of 10 years may be too short to identify the effect of screening.

Study conclusions

The findings don't support single PSA testing for population-based screening.

Project director(s):
Richard Martin
Emma Turner