Prostate-specific antigen (PSA) is a protein produced by the prostate gland, a small organ located below the bladder in males. It is normally present in the blood at very low levels.
Understanding Prostate-Specific Antigen
Prostate-specific antigen (PSA) is an enzyme produced by the prostate gland. Its main function is to liquefy semen after ejaculation, allowing sperm to move more freely by breaking down specific proteins.
While most PSA is found in semen, a small amount enters the bloodstream. Measuring blood PSA levels is a common medical practice. Elevated levels can indicate various prostate conditions, including benign prostatic hyperplasia (enlarged prostate), prostatitis (prostate inflammation), or prostate cancer.
Defining Undetectable PSA
In PSA testing, “undetectable” does not mean the complete absence of the protein. It signifies that the PSA level in the blood is below the lowest limit a specific laboratory test can reliably measure. Different PSA assays have varying sensitivities, detecting lower concentrations than others.
Common thresholds for an undetectable PSA are less than 0.1 or 0.2 nanograms per milliliter (ng/mL). These low thresholds are particularly significant after prostate cancer treatments like radical prostatectomy, which aim to remove or destroy all prostate tissue and its PSA production source.
The Meaning of an Undetectable Result
An undetectable PSA result after definitive prostate cancer treatment, such as radical prostatectomy or radiation therapy, is a positive indicator. It suggests the treatment successfully eliminated or destroyed prostate cells, including cancerous ones, that were producing PSA. This implies no detectable evidence of prostate cancer remains at the time of the test.
While an undetectable PSA indicates a favorable treatment response, it does not guarantee a permanent cure. It signifies the absence of detectable disease recurrence at that specific point. Medical professionals use this result as a marker to assess initial treatment success and monitor for any potential disease return.
Monitoring After Undetectable PSA
Even after achieving an undetectable PSA, ongoing monitoring is recommended. Regular follow-up PSA tests detect potential biochemical recurrence, defined as a rise in PSA levels after reaching their lowest point post-treatment. Such a rise indicates some prostate cells, possibly cancerous, have begun producing PSA again.
The frequency of these follow-up tests varies, typically ranging from every few months to annually, depending on the individual’s situation and medical history. A consistent PSA increase after being undetectable serves as an early warning sign that further investigation or intervention may be necessary. This vigilance helps ensure any recurrence is identified and addressed promptly.