PSA and how to treat prostate cancer

PSA and prostate cancer

PSA (prostate specific antigen) is a glycoprotein produced by intracytoplasmic vesicles of prostate epithelial cells. Under normal circumstances, there is a clear barrier between the prostate vesicles and ductal cavity and the blood circulation system. There is only a trace amount of PSA in serum, and the content in semen is higher, with a concentration of 100 times that of blood.

The concentration of PSA in the blood varies with age, 0.28ng/ml for 40-49 years old, 0.3-3.5ng/ml for 50-59 years old, 0-4.5ng/ml for 60-69 years old, and 0-6.5ng/ml for 70-79 years old. When the prostate is diseased, the tissue barrier between the prostate bubble and duct cavity and the blood circulation system is damaged to varying degrees, causing PSA protein to leak into the blood, causing the PSA concentration to increase. Prostate diseases such as prostatitis, prostate hyperplasia, prostate ischemia, etc., prostate stimulation such as rectal examination, prostate massage, cystoscopy, acute urinary retention, etc. can all cause PSA to increase. Especially when the prostate is cancerous, due to the abnormal infiltration and growth of cancer tissue, the original tissue barrier is severely damaged, causing a large amount of PSA to leak into the blood, causing it to increase significantly in the serum.

The level of PSA in serum is related to the degree of tissue barrier damage.

PSA has a high sensitivity in diagnosing prostate cancer, with a positive rate of 70% and a positive rate of 90% for advanced prostate cancer. It is generally believed that PSA has irreplaceable advantages in diagnosing prostate cancer, but it also has shortcomings, because other prostate diseases can also show positive manifestations, so it is considered to be not specific. The final diagnosis still needs to be combined with imaging, digital rectal examination and puncture biopsy histology.

PSA exists in two forms in serum, of which TPSA (total prostate-specific antigen) accounts for more than 85%, and the other FPSA (free prostate antigen) accounts for about 15%. The normal ratio of FPSA/TPSA is not uniform, and some countries set it as 0.16, while others set it as 0.19 or 0.25 as the critical value.

If the level is greater than the critical value, the possibility of prostate cancer is small, and if it is less than the critical value, the possibility of prostate cancer is high. In clinical practice, the normal value is generally set at less than 4ng/ml, and the gray area between 4-10ng/ml is a possible range for prostatitis, prostate hyperplasia, and prostate cancer. If it is greater than 10ng/ml, the possibility of cancer is high.