From the Guidelines
The most useful PSA test for monitoring prostate cancer is the percentage of free PSA (%fPSA), which has been shown to improve early detection, staging, and monitoring of the disease. This is based on the findings of the most recent and highest quality study available, which demonstrated that a 25% fPSA cutoff can detect 95% of prostate cancers while avoiding 20% of unnecessary prostate biopsies 1.
Key Measurements for Monitoring Prostate Cancer
- Total PSA: used to track treatment response and detect recurrence, with rising levels potentially indicating cancer progression
- Free PSA percentage: helps distinguish between benign conditions and cancer, with lower percentages suggesting higher cancer risk
- PSA velocity: measures how quickly PSA levels change over time, with rapid increases (>0.75 ng/mL per year) raising concern for cancer progression
- PSA doubling time: particularly valuable for monitoring after treatment, as shorter doubling times often indicate more aggressive disease
- PSA density: adjusts PSA levels relative to prostate size, helping interpret results more accurately, especially in men with enlarged prostates
Testing Intervals and Individualization
Regular testing intervals typically range from every 3-6 months for active disease to annually for stable patients, though schedules should be individualized based on risk factors, treatment history, and previous PSA patterns. For patients who have undergone radical prostatectomy, ultrasensitive PSA tests can detect extremely low PSA levels (0.01-0.1 ng/mL), allowing earlier identification of biochemical recurrence. The use of %fPSA has gained widespread clinical acceptance in the United States, specifically for patients with normal DREs who have previously undergone prostate biopsy because they had a tPSA level within the “diagnostic gray zone” 1.
From the Research
PSA Tests for Monitoring Prostate Cancer
The following PSA tests are useful for monitoring prostate cancer:
- Prostate-specific antigen (PSA) testing for early detection of prostate cancer 2
- PSA density (PSAD) for evaluating the risk of prostate cancer 3
- Free/total PSA ratio (f/t PSA) for distinguishing between benign prostatic hyperplasia and prostate cancer 3, 4
- PSA velocity (PSAV) for predicting prostate cancer and high-grade cancer after an initially negative prostate biopsy 5
- PSA density of the transition zone (PSA-TZ) for enhancing the specificity of prostate cancer detection 3
Frequency of PSA Testing
The frequency of PSA testing for monitoring prostate cancer varies:
- Three monthly PSA measurement is usually recommended for the first year after primary treatment 6
- Less frequent testing is required after the first year 6
Additional Biomarkers
Additional biomarkers, such as prostate cancer antigen 3 (PCA3) and fusion gene TMPRSS2:ERG, are being developed to distinguish between men with low-risk and those with aggressive prostate cancer 6