A variety of disorders involving the prostate cause its cells to make more prostate-specific antigen.
The prostate specific antigen, or PSA, is a specific protein that the cells of the prostate gland release into the bloodstream.
The prostate makes the liquid part of semen that helps transport sperm and also provides it with nutrition.
Small amounts leak into the bloodstream, where it can be measured.
This high amount of PSA can be measured with a blood test, thanks to a test that measures the levels of this antigen.
There are normal expected levels of PSA in the blood, elevated levels can indicate several different disorders that affect the prostate, one of which is prostate cancer .
Levels may increase in patients with prostate cancer, but elevated levels may also occur in patients with benign prostatic hypertrophy (non-cancerous prostate enlargement), prostatitis, urinary tract infection, or prostate infarction.
Elevation can also occur after prostate biopsy, aggressive digital rectal examination, ejaculation, cycling, and physical exercise.
Since PSA is tissue specific but not cancer specific.
Uses of PSA
The decision to evaluate a patient for prostate cancer using prostate specific antigen should be based on the individual situation of the patient, including age, medical history, estimated life expectancy, family history of the disease, and physical examination.
For patients who have undergone a prostatectomy (prostate + ectomy = removal) as a cancer treatment, serial prostate-specific antigen measurements can be used to detect cancer recurrence.
The serial PSA test also occurs in patients who have undergone radiation therapy rather than surgery.
Prostate specific antigen tests are used to identify the early stages of prostate cancer.
It is currently one of the few widely used tests for prostate cancer available.
The other test used to detect this cancer is a digital rectal exam, in which a doctor inserts a gloved finger into the rectum to feel the prostate to determine if it is enlarged, lumps, or abnormal areas.
The PSA tests and the digital rectal exam are usually done together to check for prostate cancer.
Studies have shown that this approach does not reduce the number of men who die from prostate cancer.
Although early identification of prostate cancer is very important, there are several significant limitations and disadvantages of PSA testing that restrict its use.
Therefore, PSA testing is done on a case-by-case basis.
Men who are at higher risk of developing prostate cancer, or men who have symptoms that may indicate cancer, are more likely to benefit from testing.
The most important risk factor for prostate cancer is age.
PSA tests are generally not done in men younger than 50 years old.
About 5-10% of prostate cancer is due to genetic defects, so men who have a family history of prostate cancer are at higher risk of developing it.
Men who have a first-degree relative (father, brother, or son) who have had prostate cancer are 2 to 3 times more likely to develop prostate cancer than men who do not have prostate cancer.
This risk may be higher if the relative was diagnosed before age 60.
Other men who are at increased risk for prostate cancer are those who have had elevated PSA tests or abnormal prostate biopsies in the past.
Men are advised to be informed about the risks and benefits of PSA tests and to make their own decisions about whether or not they should be evaluated.
Screening for PSA is most important between the ages of 55 and 69.
This test is important when you have already diagnosed prostate cancer. This is to check the treatment and see if the cancer has come back.
PSA test results
PSA levels may be elevated, and the higher the PSA level, the more likely that prostate cancer is present.
In addition, when serial prostate-specific antigen tests are performed over time, a rising antigen level is of concern for the presence of cancer.
An elevated PSA usually leads to a doctor’s recommendation to consider further testing.
These may include an ultrasound of the prostate, a cystoscopy (in which an endoscope is passed through the urethra into the penis to view the urethra and bladder), and a urinalysis to check for infection.
A prostate biopsy may also be considered, in which a urologist places a fine needle into the prostate and obtains a tissue sample that a pathologist examines under a microscope for abnormal or cancerous cells.
Results are given in nanograms per milliliter, ng / mL.
PSA levels are considered ‘normal’ for men over 40 if they are below 4 ng / ml.
Men under 40 should ideally have a PSA below 2.7 ng / ml.
PSA levels are considered “elevated” if they are above 4 ng / ml.
- 25% of men with PSA levels of 4 to 10 ng / ml have prostate cancer.
- 42-64% of men with PSA levels> 10gn / mL have prostate cancer.
If the PSA test is normal, there is no urgency for a follow-up test.
Talk to your doctor about how long to wait until another test is required.
Test results may vary based on your age, gender, health history, the method used for the test, and other things.
The test results may not mean you have a problem.
Results below 4.0 ng / ml are considered normal.
However, these age-based results are used to define normal:
- From 40 to 49 years: 0 to 2.5 ng / mL.
- Ages 50 to 59: 0 to 3.5 ng / mL.
- From 60 to 69 years: 0 to 4.5 ng / mL.
- From 70 to 79 years: 0 to 6.5 ng / mL.
Limitations of PSA testing
The PSA test is currently the most widely used method of detecting prostate cancer. Unfortunately, it has several major limitations.
Screening all men for prostate cancer has not been shown to reduce the number of people who die from this disease.
This test is not 100% reliable. Some prostate cancer patients may or may have elevated levels of prostate specific antigen.
In the same way, patients who have shown elevated levels of PSA have not developed prostate cancer.
Other (non-cancerous) conditions that cause prostate cells to produce higher levels of PSA include benign prostatic hyperplasia, urinary tract infections, and prostatitis.
Benign prostatic hyperplasia is the most common cause of elevated PSA levels. It is very common for the prostate to enlarge (hypertrophy) as a man ages.
About 80% of men will experience benign prostatic hyperplasia.
The symptoms of benign prostatic hyperplasia are caused by enlargement of the pressure of the prostate in the urethra.
This results in an altered flow of urine (dribbling, difficulty starting, stopping, and starting urination). Benign prostatic hyperplasia is not cancer and it does not cause cancer.
If a man is found to have elevated PSA levels, he will likely undergo further testing to make sure the result is not due to prostate cancer.
These tests have significant side effects, and are likely to be “unnecessary” because the cancer is not present.
Even if elevated levels of PSA are due to cancer, not all forms of prostate cancer develop and progress in the same pattern:
- The lifetime risk of developing prostate cancer is 1 in 6.
- The lifetime risk of dying from prostate cancer is 1 in 34.
Most men with prostate cancer die from another cause.
Some men have increased levels of PSA due to small deposits of cancer in their prostate that will never grow large enough to spread and cause health problems.
This is the case in 25 to 50% of prostate cancer.
Identifying this pattern of cancer is likely to result in unnecessary concern for men who choose not to investigate or treat it further.
Alternatively, men who decide to undergo more research and treatment may suffer significant side effects from the intervention.
Unfortunately, PSA tests do not identify whether cancer is definitely present, or whether it is the type that urgently needs to be treated, or the type that is harmless.
PSA in the blood
PSA can appear in the bloodstream in “free” form or it can be bound to proteins.
Normally, PSA is produced by prostate cells; then it goes through a series of changes where it kicks in, then kicks in.
The inactive form enters the bloodstream and circulates on its own (as free prostate-specific antigen).
A small amount of the active PSA enters the circulation without this complete process taking place.
Active prostate specific antigen binds rapidly to proteins in the blood and circulates in a “bound” or “complex” form.
Prostate cancer is associated with a lower concentration of free prostate-specific antigen in the bloodstream than occurs due to benign conditions such as benign prostatic hyperplasia.
Cancer disrupts the normal structure of prostate cells, resulting in increased amounts of active prostate-specific antigen that enter the bloodstream before being inactivated.
Therefore, the percentage of free (inactivated) prostate specific antigen in the circulation is reduced and there is a greater amount of bound prostate specific antigen.
The ratio of free to total prostate specific antigen has been used to improve the accuracy of prostate specific antigen tests to detect prostate cancer, especially at indeterminate levels (4.1 to 10 ng / ml).
At these levels, if the ratio of free to total PSA is low, there is a greater chance that the elevation is due to cancer rather than a benign process.
The best free to total PSA ratio to distinguish between prostate cancer and other causes of elevated PSA is unknown.
It has been suggested that the use of free prostate-specific antigen levels to determine the need for a biopsy is only clinically useful at ‘extreme’ levels, although these have not been clearly described.
Free prostate-specific antigen levels (<14%) associated with more aggressive forms of prostate cancer may also be significantly lower, although the application of this finding requires further study.
Free prostate specific antigen must be specifically ordered in the laboratory form, and will only be performed by some laboratories if the total PSA level is between 4 and 10 ng / ml.
The total prostate specific antigen is ordered and reported separately, and the percentage of free prostate specific antigen is given.
Many laboratories report that for total PSA levels of 4 to 10 ng / ml and if the free / total PSA is less than 10%, prostate cancer is likely.
At values> 25% of free / total PSA, benign prostatic hyperplasia is more likely.
Prostate Specific Antigen Test Procedure
Prostate specific antigen is detected using a simple blood test. A blood sample is drawn, this procedure takes 3 to 5 minutes.
The blood is sent in a test tube to a laboratory for analysis.
Test results can be affected by:
- An infection.
- The use of some medications.
- Riding a bike before the test.
- Ejaculation before the test.
You may need to abstain from sex and not ride a bike within 1 to 2 days before the test.
In addition, all medications, herbs, vitamins, and supplements that you are taking should be reported to the doctor.
This includes medicines that do not need a prescription and any illegal drugs that you may use.
Abnormal levels in the prostate specific antigen test
If a PSA level is high for a man’s age, the test will usually be repeated. If it is still elevated, a transrectal ultrasound may be done.
Generally, the next stage in testing is a prostate biopsy. Further treatment will depend on the results of the biopsy.
If prostate cancer is found, treatment options include waiting and managing the cancer, surgery, radiation therapy, hormonal medication, and other treatments.
Factors such as the location of the cancer, how aggressive it is, determined by the Gleason score, which is a grading system based on how cancerous prostate tissue appears under the microscope, the age of the man, and other medical factors. into account when determining the most appropriate treatment.
The prostate is a gland that wraps around the urethra (the tube in the penis through which urine and semen pass) at the base of the bladder.
In healthy men, the prostate is slightly larger than a walnut.
Cancer can develop within the cells of the prostate gland, this is called prostate cancer.
Early detection of aggressive prostate cancer through PSA testing can allow the disease to be treated early enough that it can be cured.
PSA levels can rise 5-10 years before prostate cancer produces any symptoms.
Early detection can also reduce the risk of complications due to treatment of the disease or the disease itself.
Leading to a better quality of life for the patient.
The risks associated with PSA testing are generally related to the consequences of the results.
False positive tests (increased PSA, but not cancer cells) can lead to unnecessary research or treatment, which can have serious side effects.
Prostate biopsy rarely causes complications requiring hospitalization (<1%), but test-related anxiety and short-term pain are common.
Even when a prostate biopsy is negative, it can cause significant chronic distress and anxiety.
Although prostate cancer treatment (removal of the prostate gland or radiation therapy) rarely causes death, significant complications include sexual dysfunction, bowel problems, and urinary incontinence.
Sexual dysfunction can occur in 20-70% of patients and urinary problems in 15-50% of patients after radical prostatectomy.
Radiation therapy can cause sexual dysfunction in 20 to 45% of cases, urinary incontinence in 2 to 16%, and intestines.
Some forms of prostate cancer spread so slowly that the disease does not cause health problems, and the man who has it dies of something unrelated.
Treating this type of cancer does not change this result and may also cause side effects.
Furthermore, false positive tests or the discovery of “non-threatening” cancer are likely to create unnecessary worry and stress.