The PSA is a protein produced by epithelial cells of the prostate and can be measured in the blood and used as a tumor marker.
The total PSA (tPSA) is considered normal if less than 4ng/ml but it is not a reliable indicator of presence or absence of prostate cancer.
An abnormal tPSA should always be confirmed to exclude spurious laboratory results before embarking upon a possible prostate biopsy.
About 30% of men who have a tPSA between 4-10 ng/ml will have a prostate cancer but about 70% will not.
Also,about 15% or more of men with a tPSA less than 4ng/ml will have a clinically significant but localized prostate cancer. About 2% of these men will have a very aggressive prostate cancer.
The use of the %free PSA (calculated from the tPSA and the free PSA) may improve the accuracy of this blood test in prostate cancer screening. The PCa3 test may also prove to be a useful marker.
The level of the tPSA in the blood can be lowered by various medicines such as Statins,NSAIDS,Thiazides and 5 alpha reductase inhibitors such as proscar and avodart. This lowering of the tPSA by these medicines does not necessarily lower the risk for prostate cancer.
In contrast,the tPSA can be elevated in men with a large prostate,by inflammation in the prostate, a urine infection, after a digital rectal examination, a prostate biopsy or after ejaculation, without the presence of an underlying prostate cancer.
Despite the limitations of the tPSA as a reliable test for prostate cancer screening the test is still useful especially when the
%free component is also measured. The more prostate cancers are detected when still localized,the greater the likelihood that treatment options such as HIFU can afford a cure. After total treatment of the prostate cancer, follow up monitoring of his PSA is very reliable.