From the Guidelines
A Prostate-Specific Antigen (PSA) test shows the level of PSA in a man's blood, which can help detect prostate cancer early, as well as provide information about other prostate conditions, but it is not definitive for cancer diagnosis on its own. The test measures the level of PSA, a protein produced by both cancerous and noncancerous tissue in the prostate gland 1. Normal PSA levels typically range from 0 to 4 nanograms per milliliter (ng/mL), though this can vary by age. Higher PSA levels may indicate prostate cancer, but can also result from benign conditions like prostatitis (inflammation of the prostate), benign prostatic hyperplasia (enlarged prostate), or recent ejaculation.
Some key points to consider when interpreting PSA test results include:
- The sensitivity and specificity of PSA levels for detecting any prostate cancer, with a sensitivity of about 32% and a specificity of about 87% at a cut-off of 3.1 ng/mL 1
- The fact that only about 25% of men with PSA in the 4 to 10 ng/mL range have a subsequent positive biopsy 1
- The importance of monitoring PSA levels over time to detect concerning trends, rather than relying on a single test result 1
- The use of PSA testing in combination with other diagnostic tools, such as digital rectal exams or prostate biopsies, to improve the accuracy of prostate cancer diagnosis 1
It's also important to note that PSA testing is generally recommended for men over 50, or earlier for those with risk factors such as family history or African American ethnicity 1. The test requires a simple blood draw and no special preparation, making it a convenient screening tool despite its limitations in specificity. Overall, a PSA test is a useful tool for detecting prostate cancer early, but it should be used in conjunction with other diagnostic tools and interpreted in the context of a man's individual risk factors and medical history.
From the Research
What does a PSA test show
- A Prostate-Specific Antigen (PSA) test measures the level of PSA in a man's blood, which can be elevated in men with prostatic disease, including cancer 2.
- The test is not cancer-specific and can be elevated due to other conditions such as prostatitis, benign prostatic hypertrophy, and other non-cancerous conditions 3.
- A PSA test can show:
- Elevated PSA levels, which may indicate prostate cancer, but can also be caused by other conditions 4.
- The level of PSA in the blood, which can be used to monitor disease progression or recurrence, but absolute levels are rarely meaningful 3.
- Changes in PSA levels over time, which can provide insight into the presence of prostate cancer, but not definitive proof 3.
Limitations of PSA testing
- PSA testing has limitations, including a high frequency of falsely elevated values in men with benign prostatic hyperplasia (BPH) 4.
- The test can be affected by hormonal control, drug therapy, stage of disease, and genetic factors, which can lead to varying PSA levels in different men 3.
- PSA determination should be obtained after complete clinical resolution of inflammation to exclude prostatic malignant involvement 5.