There is a higher probability of developing prostate cancer as the amount of PSA in the blood increases:
PSA 0-2 ng/mL | Cancer Percentage 1%
PSA 2-4 ng/mL | Cancer Percentage 15%
PSA 4-10 ng/mL | Cancer Percentage 25%
PSA >10 ng/mL | Cancer Percentage >50%
The most frequent value used as upper limit of normal values is 4 ng / mL (nanograms per millilitre).
However, higher concentrations of PSA are normal in older men because the prostate gland enlarges with age and produces more PSA. The normal value of 4 ng / mL is perhaps too high for young men.
Levels over 10 ng / mL increase the probability of cancer dramatically, so follow-up monitoring is recommended.
A small percentage of prostate cancers do not produce detectable increases of PSA in the blood, even when the disease is in advanced stages. Therefore, it is important to not rely exclusively on this laboratory test.
However, not all patients who have a high PSA level will develop prostate cancer, as it may be raised by other causes, such as an infection of the urinary tract or the prostate.
In addition to the PSA test, patients should undergo a digital rectal exam of the prostate, carried out by a urologist.