Men anticipate prostate cancer screening with all the dread that women bring to Pap tests. Screening is generally limited to men over the age of 50 (unless there is a history of early prostate cancer in a father or brother) and consists of an exam of that part of the prostate that can be reached by a probing finger plus a blood test for prostate specific antigen or PSA.
The problem is that the PSA, while being the only cancer marker test currently available for screening purposes, is not specific. In other words, most men with an elevated PSA do not have cancer. The digital exam is even less specific as many aging men have enlarged prostates without harboring cancer. Other screening deficiencies in our current approach of one blood test and one finger exploration include:
- Most men with prostate cancer (85% in one study) detected by PSA screening could avoid therapy. Per another study, one would have to screen 1400 men and perform 50 prostatectomies to prevent one death from prostate cancer.
- There is no PSA level below which the risk of cancer is zero. The Prostate Cancer Prevention Trial (PCPT) found cancer in 6.6% of men with PSAs below .5 and 12.5% of those men had aggressive cancer.
- Other factors seem to affect PSA levels, e.g. obesity and statin use lower PSA.
Dr. Klein suggests one approach to screening that uses seven variables to predict a man's risk of currently having prostate cancer. This test can be found at PCPT risk calculator.
1. Klein, EA. What's new in prostate cancer screening and prevention? Cleveland Clinic Journal of Medicine. Vol 76 August 2009 439-445.