Prostate-Specific Antigen (PSA) is a protein produced primarily by prostate cells. After a radical prostatectomy—the surgical removal of the entire prostate gland—monitoring PSA levels is standard practice. The purpose of post-operative PSA surveillance is to determine if the surgery successfully removed all cancerous tissue and to detect any potential recurrence early. A normal result after this procedure is not a number within a typical range, but rather a number that approaches zero.
The Immediate Goal: Defining Undetectable PSA
The most favorable outcome following a radical prostatectomy is for the PSA level to become virtually undetectable. Since the gland that produces the vast majority of the PSA protein has been removed, the amount remaining in the bloodstream should drop substantially. This drop typically occurs within six to eight weeks following the operation.
Modern, highly sensitive laboratory tests define an undetectable PSA as a level typically less than \(0.1\) nanograms per milliliter (ng/mL), and sometimes even below \(0.05\) ng/mL, depending on the specific assay used. While trace amounts of PSA can be produced by other cells in the body, a sustained undetectable reading suggests the treatment was successful in eradicating the cancer cells.
Understanding Biochemical Recurrence
A rising PSA level after the initial drop is the first indication that microscopic prostate cancer cells may have survived the surgery or were outside the prostate at the time of removal. This phenomenon is termed biochemical recurrence (BCR). The most widely accepted definition for BCR following a radical prostatectomy is a confirmed PSA level of \(0.2\) ng/mL or greater.
This designation usually requires two consecutive measurements at or above this \(0.2\) ng/mL level to confirm the trend and rule out minor fluctuations. A rising PSA does not immediately mean the cancer is widespread, but rather that a biological process related to prostate cells is active in the body. Identifying recurrence when the PSA level is low allows for the most effective follow-up treatment. Patients who experience BCR often have no physical symptoms, which underscores the importance of routine blood testing for surveillance.
Monitoring Schedule and Testing Frequency
Following the procedure, a patient’s first PSA test is typically scheduled about six to twelve weeks after surgery, once the protein has had time to clear from the bloodstream. For the first two to three years, the most common monitoring schedule involves testing every three to six months. Frequent testing is necessary because most recurrences happen within this early timeframe.
As time passes and the PSA remains undetectable, the testing frequency can be gradually reduced. After the five-year mark, surveillance often shifts to an annual PSA measurement. To ensure accurate comparisons and track trends effectively, it is recommended that patients use the same clinical laboratory for all their PSA tests.
Initial Steps Following a Rising PSA
When a patient’s PSA meets the threshold for biochemical recurrence, the medical team begins a structured evaluation process. The physician will first confirm the rising trend with a second blood test to ensure the result is reliable. Following confirmation, the physician will review the original surgical pathology report for indicators of recurrence risk, such as the tumor grade and whether cancer cells were found at the margins of the removed tissue.
If the PSA level continues to rise, the next phase involves imaging studies to pinpoint the location of the recurrent disease. Newer imaging technologies, such as Prostate-Specific Membrane Antigen (PSMA) PET scans, are highly sensitive and can detect recurrent cancer at very low PSA levels, sometimes even below \(0.5\) ng/mL. The primary follow-up treatment often involves salvage radiation therapy, which targets the area where the prostate gland was located, known as the prostatic bed. This treatment is most effective when initiated while the PSA level is still low. In cases where the recurrence is more widespread or rapidly progressing, hormonal therapy may be introduced as an additional treatment option.