Questions and Answers

What is the difference between the PCA3 test and PSA?

Answer by the PCA3 Editorial Board
Prof. Jack Schalken
Prof. Bertrand Tombal
Prof. Hendrik Van Poppel

The major difference between PCA3 (Prostate CAncer gene 3) and prostate specific antigen (PSA) is the fact that PCA3 is prostate cancer (PCa)-specific and PSA is not.

This is due to the fact that PSA is also produced by non-cancerous prostate cells. Therefore, PSA is not only elevated (higher than 2.5-6.5 ng/mL depending on age) in men with PCa but also in men with non-cancerous prostate diseases. These include benign prostatic hyperplasia (BPH, i.e. prostate enlargement) or prostatitis (infection of the prostate). The greater the number of prostate cells / size of the prostate, the higher the PSA level in the blood. As a consequence, many men with a PSA level between the age-specific upper limit of normal and 10 ng/mL do not have PCa, i.e. the prostate biopsy is negative / does not contain cancer cells. Prostate biopsy may cause pain, bleeding and infection. Therefore, there is a need for additional tests that will help to avoid unnecessary biopsies in these men.

PCA3 is, unlike PSA, only produced by PCa cells and not affected by prostate size. Therefore, the PCA3 Score better than PSA predicts the presence of PCa in a subsequent biopsy. As such, it will help to reduce the number of unnecessary biopsies and its potential discomfort, pain and complications (pain, bleeding and infections).

More info: PCA3 background information