PSA usually refers to Prostate-Specific Antigen.
What it is:
- A glycoprotein enzyme (serine protease) produced by epithelial cells of the prostate gland.
- Its normal function is to liquefy semen for sperm motility.
Clinical Use:
- Biomarker for prostate conditions:
- Prostate cancer → PSA is often elevated.
- Benign prostatic hyperplasia (BPH) and prostatitis can also increase PSA (not cancer-specific).
- Screening & diagnosis:
- Used with digital rectal exam (DRE) for prostate cancer screening.
- Not fully specific — false positives can occur.
- Monitoring:
- Response to prostate cancer treatment (e.g., androgen deprivation therapy, chemotherapy, abiraterone, enzalutamide).
- Detecting biochemical recurrence after prostatectomy or radiation.
Reference Values (general guidance):
- Normal: < 4 ng/mL (but thresholds vary with age and risk factors).
- PSA velocity (rate of increase) and PSA doubling time are also clinically important.
Role for Oncology Pharmacist:
- Recognize PSA trends as treatment response markers in prostate cancer.
- Educate patients that PSA is not cancer-specific and can be influenced by drugs (e.g., 5-alpha reductase inhibitors like finasteride ↓ PSA by ~50%).
- Monitor PSA along with imaging and symptoms for disease progression or remission