From the Guidelines
The blood test for prostate cancer is the Prostate-Specific Antigen (PSA) test. This test measures the level of PSA, a protein produced by the prostate gland, in a man's blood. Elevated PSA levels may indicate prostate cancer, though other conditions like prostatitis (inflammation of the prostate) or benign prostatic hyperplasia (enlarged prostate) can also cause PSA levels to rise. Normal PSA levels typically range from 0 to 4 nanograms per milliliter (ng/mL), though what's considered "normal" may vary with age 1. Some key points to consider when interpreting PSA test results include:
- Men with PSA levels between 4 and 10 ng/mL have about a 25% chance of having prostate cancer, while those with levels above 10 ng/mL have a greater than 50% chance 1.
- The PSA test is often used alongside a digital rectal exam (DRE) for prostate cancer screening.
- If these tests suggest cancer, additional testing such as prostate biopsy may be recommended. It's essential to discuss the benefits and limitations of PSA testing with your healthcare provider, as it can sometimes lead to overdiagnosis of slow-growing cancers that might never cause problems 1. When deciding whether to undergo PSA testing, men should consider the potential benefits and harms, including the risk of false-positive results, overdiagnosis, and treatment-related complications. The American College of Physicians recommends that clinicians inform men between the ages of 50 and 69 about the limited potential benefits and substantial harms of screening for prostate cancer, and base the decision to screen on the risk for prostate cancer, a discussion of the benefits and harms of screening, the patient's general health and life expectancy, and patient preferences 1.
From the Research
Blood Test for Prostate Cancer
- The blood test commonly used to detect prostate cancer is the Prostate-Specific Antigen (PSA) test 2, 3, 4, 5, 6.
- The PSA test measures the level of PSA in the blood, which can be elevated in men with prostate cancer 2, 3, 4.
- A high PSA level can indicate the presence of prostate cancer, but it can also be caused by other conditions such as benign prostatic hyperplasia (BPH) or prostatitis 2, 3, 4.
Interpretation of PSA Results
- The interpretation of PSA results can vary depending on the individual and the treatment received 3, 4, 5.
- A PSA level of less than 4 ng/mL is generally considered normal, while a level above 10 ng/mL is considered elevated 2, 3, 4.
- The rate of change of PSA levels over time, known as PSA velocity, can also be used to assess the risk of prostate cancer 4, 5.
PSA Kinetics After Treatment
- After radiation therapy, PSA levels can take several months to decrease and may not reach a nadir (lowest level) for up to 2 years 5.
- The incidence of PSA bounce (a temporary increase in PSA levels) after radiation therapy can range from 10-20% 5, 6.
- Understanding PSA kinetics after treatment is important for assessing treatment response and monitoring for disease recurrence 5, 6.