Revised 18 May 2012
Serum PSA is widely used to aid detection of prostate cancer. Unfortunately it is not a particularly good screening test, with a positive predictive value of ~25%. While it is an independent predictor of disease progression and treatment failure, serum PSA does not distinguish between clinically indolent cancers and those that may go on to cause death.
A continuum of prostate cancer risk exists with varying PSA levels, and ‘normal’ levels vary by age.
PSA level (ng/ml) | Prostate cancer prevalence % | | Age (years) | Age-specific median value |
<1 | 6-10% | | 40-50 yrs | 0.7ng/ml |
1-4 | 17-25% | | 50-60 | 0.9ng/ml |
4-10 | 20-30% | | 60-70 | 1.2ng/ml |
>20 | 80% | | >70 | 1.5ng/ml |
Age-adjusted reference ranges, PSA velocity (rate of change over time), free/total PSA ratio, and PSA density (PSA level relative to gland volume) improves the sensitivity and specificity of PSA as a screening test. Currently, individualized risk assessments of not only of prostate cancer but also of “significant” prostate cancer, is based on these determinants of PSA, as well as digital rectal examination (DRE) of the prostate, patient age, co-morbidities, family history, ethnicity, and prior biopsy history. These refinements have not been subject to randomized studies. Men who are interested in their risk of prostate cancer should consider using an on-line risk calculator such as Your Prostate Cancer Risk Calculator.
