Prostate-specific antigen (PSA) is a protein made by the prostate. It helps to thin the sperm and promote the movement of spermatozoa. It is a blood marker for prostate cancer but not only…
PSA is a blood marker for prostate cancer. It can help in the diagnosis and follow-up of patients already diagnosed. “But its increase does not mean in 100% of cases that there is cancer. It can also increase in the case of prostatitis (inflammation of the prostate, editor’s note)” notes Dr. Natacha Naoun, oncologist specializing in Genito-Urinary oncology at the Gustave Roussy Institute.
Prostate specific antigen, or PSAis a protein made by the prostate. It helps to thin the sperm and promote the movement of spermatozoa. It is found in small quantities in the blood of men. A high level of prostate antigen is suggestive of a prostate abnormality. Some are benign, like benign prostate hypertrophy or adenoma (enlargement), others are malignant like prostate cancer. Depending on the PSA level and various criteria such as age or symptoms, other tests may be performed, such as a trans-urethral biopsy. Systematic monitoring of PSA is not recommended in men but is regularly offered by doctors after the age of 50.. Prostate cancer remains the most common in men, ahead of lung cancer or colorectal cancer.
“A high level of prostate antigen is suggestive of a prostate abnormality”
The average normal value of the PSA level depends on the technique used. She is from the order of 4 ng/mL of blood. The normal PSA level varies depending on the age of the patient: it is 2.5 ng/mL for men under 50, 3.5 ng/mL for men aged 50-60 and 4.5 ng/mL for men aged 60-70.
| Age | normal rate |
|---|---|
| Men under 50 | 2.5ng/ml |
| Men between 50 and 60 years old | 3.5ng/ml |
| Men between 60 and 70 years old | 4.5ng/ml |
The prostate-specific antigen assay is performed by a simple blood test. It is recommended not to have sexual intercourse the day before the test and not to have had a digital rectal examination in the previous 3 days, as this can increase the PSA level. Doctors urologists recommend performing a PSA assay and a digital rectal exam in all men over 50 and under 75. The dosage of PSA (exclusively prostatic protein) makes it possible to evoke the diagnosis and to follow the evolution of prostate cancer. A normal dosage does not exclude the presence of a prostate tumor : a digital rectal examination can check the volume and appearance of the prostate. The PSA assay is not 100% reliable: a prostate biopsy is essential to confirm the diagnosis.
Blood levels of prostate-specific antigen may increase in the following cases:
- prostate tumor,
- acute or chronic prostatitis (prostate infection),
- adenoma or benign prostatic hypertrophy, (enlargement of the prostate),
- inflammation of the prostate,
- recent ejaculation,
- Rectal touch.
The blood test for prostate specific antigen is used for screening for prostate cancer because it represents a tumor marker. Its increase is sometimes associated with urinary symptoms such as urgency or urinary tract infections. It can also be used as part of prostate cancer monitoring, following the implementation of a treatment. “If the PSA level is high on a first assay, it will be rechecked” says Dr Natacha Naoun.
A PSA level below normal is rare and insignificant except when it comes to the fraction of free PSA. Indeed, a lowered rate of free PSA is an argument in favor of a possible prostate cancer and this requires additional examinations.
The Haute Autorité de Santé indicates that systematic screening for prostate cancer, carried out by assaying the prostate-specific antigen, has not shown any benefit. However, it is recommended to consult when a high PSA level is found during a routine check-up, or when urinary or sexual symptoms are present. “Its increase does not mean 100% of cases that there is cancer since it can increase for other reasons” emphasizes Dr. Naoun who agrees that “It is an aid to the diagnosis of prostate cancer but it does not pose it. It is an indicator for other complementary examinations”. In men over 50, a consultation is necessary when there is a change in urination (urinary urgency, heaviness, urinary or sexual difficulties).
Thanks to Dr Natacha Naoun, oncologist specialized in Genito-Urinary oncology at the Gustave Roussy Institute.