Prostate-Specific Antigen (PSA) is a protein produced by the prostate gland. This protein’s primary function involves the liquefaction of seminal fluid, aiding sperm mobility. PSA is present in the bloodstream, and its levels are measured to help assess prostate health.
PSA testing helps clinicians detect prostate cancer earlier, when treatment options are often more effective. While PSA is specific to the prostate gland, it is not specific to prostate cancer alone. Both healthy and cancerous prostate cells produce PSA, and elevated levels can indicate various prostate conditions.
Defining Undetectable PSA
The term “undetectable PSA” after prostate cancer treatment signifies that the level of prostate-specific antigen in the blood is extremely low, falling below the sensitivity threshold of the laboratory test. For many modern, highly sensitive assays, a reading of 0.02 ng/mL (nanograms per milliliter) is often considered within this “undetectable” range, or very close to it.
Laboratories might report a value like 0.02 ng/mL instead of a true 0.0 ng/mL due to the inherent precision limits of the testing equipment. Ultrasensitive PSA tests can detect even minute quantities, sometimes as low as 0.003 ng/mL. After a radical prostatectomy, PSA levels are expected to drop to virtually undetectable levels, often below 0.05 or 0.1 ng/mL, within six to eight weeks.
Factors Affecting PSA Levels
Even at very low ranges, several factors unrelated to cancer can influence PSA levels. Inflammation of any remaining prostate tissue, known as prostatitis, can cause a slight elevation in PSA. Benign prostatic hyperplasia (BPH), an enlargement of the prostate, can also contribute to detectable PSA if some prostate tissue remains after treatment.
Physical activities or manipulations of the prostate can also temporarily affect PSA readings. These benign influences are generally considered by healthcare providers when interpreting very low PSA results.
Implications of a 0.02 PSA Reading
For a patient who has undergone prostate cancer treatment, such as a radical prostatectomy or radiation therapy, a PSA reading of 0.02 ng/mL is generally viewed as a favorable outcome. This very low reading typically suggests successful treatment and a very low likelihood of cancer recurrence. After a prostatectomy, the goal is for PSA levels to fall to near zero because the primary source of PSA production has been removed.
This low reading falls well below the thresholds typically used to define biochemical recurrence (BCR), which is generally considered a confirmed PSA level of 0.2 ng/mL or greater after prostatectomy. A stable 0.02 ng/mL reading over successive tests is more reassuring than a rising trend, even if the value remains very low. The maintenance of a post-prostatectomy PSA below 0.01 ng/mL has been associated with a high likelihood of long-term disease-free survival.
Monitoring and Follow-Up After Treatment
Following prostate cancer treatment, regular PSA monitoring is part of long-term follow-up care. After a prostatectomy, PSA levels are typically checked every three to twelve months, with the first test usually performed within six to eight weeks post-surgery. The treating physician interprets these results, considering the patient’s individual history and the trend of PSA levels over time.
While an undetectable PSA is a positive sign, continued surveillance is necessary. A rising PSA, even from very low levels, warrants further investigation. Patients often experience “PSA anxiety” between tests, making open communication with their healthcare team about results and expectations important.