Prostate-Specific Antigen (PSA) is a protein that exists in epithelium in prostate only and can be tested easily through blood test.

PSA is used to detect prostate cancer early even before any clinical symptoms occur to initiate early treatment to increase chances of full recovery.

The normal PSA range for males above the 50 year-old is 4 ng/ml.

Reasons for Increases in PSA

• Urethritis.
• Prostate infection.
• Benign prostate hypertrophy.
• Prostate cancer.

Prostate checkups: biopsy through rectal ultrasound, transperineal body biopsy, transurethral resection of prostatectomy, cystoscopy, prostate massage can lead to PSA increases.

Abnormal PSA value does not mean having prostate cancer, but having a higher risk of having this disease. Biopsy is required for further diagnosis.

How to Interpret PSA Index

Reports from Western countries indicate that when PSA value falls between 4.1-9.9 ng/ml, obtained from biopsy through rectal ultrasound, the chance of having prostate cancer is 1/3, while PSA ≧ 10.0 ng/ml, the chance increase above ½.

Although people in Taiwan have lower rate of having prostate cancer than those in Western countries, it is still crucial to keep track of abnormal PSA values. Physicians will decide if to have biopsy through rectal ultrasound after evaluating patient’s age, medical history, and the results of digital rectal examination (DRE).

It is not completely risk free to have prostate biopsy through rectal ultrasound; thus, it has been the research focus as to whether having biopsy on patients with normal DRE results, while PSA value is higher than 4.0 ng/ml (4.1-9.9 ng/ml).

Increase Diagnosis Accuracy

There are methods to reduce unnecessary biopsy to increase positive diagnosis of biopsy.

• Adjust PSA Reference Value Based on Age

Age-specific PSA cutoff values refers to having “different standard value” based on “different ages”. Benign prostate hypertrophy increases with age and it secrets PSA to cause higher PSA. In other word, the normal PSA of an eighty years old should be higher than that of a sixty year-old.

PSA Velocity

It is important to keep tracking of PSA velocity for at least one or half year. Chances are it is benign when the average velocity is less than 0.75 ng/ml each year.

It is clinically discovered that patients with prostate cancer have higher PSA velocity than other. When it is not certain if a patient with abnormal PSA has prostate cancer, doctors will test PSA at different times to see if the velocity is faster than normal to interpret if the patient possibly has prostate cancer.

Free PSA/Total PSA Ratio

Doctors now use free PSA (fPSA)/total PSA (tPSA) ratio for interpretation. Some PSA does not integrate with protein in blood. Under the circumstance of cancer, the fPSA/tPSA ratio lowers; therefore, the possibility of cancer increases when it is lower than a certain value.

In other word, the possibility is higher to be benign when fPSA/tPSA ratio is greater than 0.25.

Conclusion

PSA not only contributes tremendously to prostate cancer diagnosis, but also follow up after treatments. Doctors often interpret if the cancer is under control or relapse by keeping track of PSA periodically.

Although PSA has very high accuracy, it is not exclusive to prostate cancer. PSA might increase on patients with benign prostate hypertrophy and bladder infection, or patients with catheter.