Prostate-Specific Antigen (PSA) is the Most Important Tumor Marker for Adult Males
PSA is the reference tumor marker for adult males, particularly for prostate cancer detection, staging, and monitoring. 1
PSA as the Primary Tumor Marker for Males
- PSA is a serum glycoprotein produced exclusively by prostatic tissue, making it the most clinically useful and widely used tumor marker in urology today 2
- The National Comprehensive Cancer Network (NCCN) recommends PSA as the reference marker for prostate cancer detection 1
- PSA testing is recommended as a baseline at age 45-75 years, with follow-up intervals based on initial results 1
Clinical Applications of PSA Testing
Screening and Early Detection
- PSA with a cutoff at 3 ng/ml is the base for selecting candidates for prostate biopsy in men suitable for curative treatment 3
- For PSA <1 ng/mL, repeat testing at 2-4 year intervals is recommended; for PSA ≥1 ng/mL, more frequent monitoring is advised 1
- PSA screening should be used in conjunction with digital rectal examination for optimal cancer detection 1
Risk Stratification and Monitoring
- PSA is most useful for cancer staging when combined with clinical stage and Gleason score in multivariate analysis 2
- PSA doubling time is a critical prognostic factor in biochemical recurrence, with shorter doubling times correlating with higher risk of metastatic progression 4
- After treatment, PSA is the most sensitive method for monitoring disease recurrence 2
Enhanced PSA Testing Methods
Percent Free PSA
- Free (unbound) PSA expressed as a ratio of total PSA improves specificity for prostate cancer detection 3
- The FDA approved percent free PSA for early detection of prostate cancer in men with PSA levels between 4 and 10 ng/mL 3
- A 25% free PSA cutoff detects 95% of prostate cancers while avoiding 20% of unnecessary prostate biopsies 3
PSA Density
- PSA density (PSAD) requires measurement of prostate volume through transrectal ultrasound 3
- PSAD is expressed as PSA value (ng/mL) divided by prostate volume (cm³) 3
- A PSAD cutoff of 0.15 mg/mL/cc³ can help differentiate between benign prostatic hyperplasia and prostate cancer 3
PSA Velocity
- PSA velocity (rate of change over time) can improve prostate cancer detection when 3 serial PSA values are measured during a 2-year period 2
- PSA velocity ≥0.75 ng/mL yearly increases sensitivity of PSA testing from 66% to 79% in men with PSA less than 4 ng/mL 3
Important Clinical Considerations
- 5α-reductase inhibitors (finasteride and dutasteride) decrease PSA by approximately 50%, requiring PSA value adjustment when interpreting results 1
- Age-specific PSA reference ranges can improve sensitivity for prostate cancer detection in young men and specificity in older men 2
- Testing above age 75 should be done with caution and only in very healthy men with little comorbidity 1
Other Tumor Markers in Males
- For testicular cancer and germ cell tumors, α-fetoprotein (AFP), human chorionic gonadotropin (hCG), and lactate dehydrogenase (LDH) are the recommended markers 3
- These markers should be measured before and after orchiectomy and before chemotherapy for patients with nonseminomas 3
- CA 19.9, CEA, and CA 15.3 are not recommended for general cancer screening in males due to insufficient sensitivity and specificity 1
Pitfalls to Avoid
- PSA is not cancer-specific but prostate-specific, leading to false positives in conditions like benign prostatic hyperplasia 2
- Avoid using PSA as a single tool for screening without considering other clinical factors 5
- Be aware of false-positive elevations of tumor markers from non-malignant conditions (e.g., hepatitis causing AFP elevation, pituitary hCG production in hypogonadism) 3