Diagnostic Use
PSA is used for diagnosis, monitoring and detecting recurrence of prostatic cancer. It should be used in conjunction with a full clinical examination, including a rectal examination.
Screening for prostate cancer:
Whether the benefits of screening asymptomatic men using PSA outweigh the harms, is unresolved and a matter of ongoing debate. A positive PSA screening test usually will lead to a prostate biopsy. If cancer is found, various therapies including surgery, radiotherapy, hormonal and chemotherapy may be employed. These therapies often impair quality of life because of side effects including impotence and incontinence.
On the other hand, prostate cancer often progresses very slowly and the majority of men who get prostate cancer do not die of the disease, but of other causes. For every man whose life is prolonged by screening, there will be many men left with impotence and/or incontinence. For all these reasons, many men choose not to have PSA screening.
Patients are advised to discuss all these matters with their doctor before deciding whether to have a PSA screening test.
Interpretation
Refer to the most up-to-date Te Whatu Ora guidance for referral thresholds.
While PSA may be elevated in prostate cancer, it is also increased in benign prostatic hypertrophy, and levels in this condition overlap with those seen in cancer. PSA levels >10 ug/L make prostate cancer more likely than BHP. Prostatitis or vigorous prostatic massage may cause elevations of PSA; these usually return to normal within a few weeks. The in vivo half-life of PSA is 2 – 3 days.
An increase in PSA of more than 1.5 ug/L per year is suspicious and warrants referral to a urologist.
Test Method
Performed in LabPlus Automation
Principle: Sandwich type immunoassay with chemiluminescence detection
Reagents: Roche assay
Analyser: Roche Cobas