How to analyze your PSA (or APS) assay?
Discover in this sheet the symptoms and the tests that make it possible to make a diagnosis of prostate cancer.
Prostate cancer, what is it?
The prostate is a gland of the male reproductive system. It is located just below the bladder and, like a ring, surrounds the urethra, the channel through which urine and semen exit the body.
The role of the prostate is to produce prostatic fluid, one of the components of semen with seminal fluid and spermatozoa, to temporarily store semen before ejaculation, then to contract at the time of ejaculation, thus participating in the expulsion of sperm.
Prostate cancer is the most common type of cancer in men: it is estimated that 1 in 7 men will be diagnosed with it, most often in their 60s. Although no particular cause has been discovered, there is a genetic predisposition.
Most prostate cancers grow very slowly. Moreover, the vast majority of men in whom this cancer is detected will die of another cause. Very often, the tumor remains localized in the prostate and has limited effects on health, sometimes causing urinary or erectile problems. However, some cancers may grow and spread more quickly.
In France, prostate cancer is the most common cancer in men (71,200 new cases estimated in 2011) and the third leading cause of cancer death in men (8,700 deaths per year).
The median age of diagnosis is 74 years, and 44% of prostate cancers are diagnosed after 75 years. The average age of death linked to prostate cancer is 78 years, which is almost the average life expectancy of men in France.
Prostate cancer is a cancer with a good prognosis: relative 5-year survival has improved dramatically, from 70% for cases diagnosed in 1990 to 90% in 2002.
Prostate cancer is the second leading cause of male cancer death in North America, after lung cancer.
The different types of prostate cancer
Adenocarcinoma is the most common form of prostate cancer. It accounts for approximately 95% of cases.
The severity of the cancer depends on the extent of the tumor (local, with nearby or distant metastases) and the type of cancer cells. There is a score to measure the prognosis of prostate cancer, that is- i.e. the risks it presents to the affected person. This is the Gleason score.
This score assigns two numbers from 3 to 5 during microscopic examination of prostate tissue, numbers corresponding to grades 3, 4 or 5. The number 3 corresponding to more benign prostate tissue and the number 5 to the most aggressive. With these figures, to obtain a score which can range from 2 to 10, the sum of 2 grades is added, that of the most frequent cell populations in the prostate and the highest score observed.
Thus, a score of 6 (1-1) corresponds to a less aggressive cancer, 7 a little more, and the higher the number, the more the aggressiveness of the tumor increases. This figure is important in determining the choice of the most suitable treatment for each man.
Prostate cancer: how to diagnose it?
It measures the rate of prostate antigen (APS or PSA). Prostate cancer can be detected by observing an increase in a protein in the blood: prostate-specific antigen or PSA. PSA is a substance produced by the prostate.
However, a high result on this test does not necessarily mean that there is cancer. Indeed, an amount of more than 4 nanograms/ml of this protein in the blood is associated with prostate cancer in about 25% of cases, and with another prostate disorder in 75% of cases.
In the case where it is not cancer, a high PSA may correspond to benign prostatic hyperplasia, inflammation or infection of the prostate. On the other hand, the PSA assay does not detect all cases of cancer.
In a study evaluating the effectiveness of the PSA test, 15% of men who tested negative for this test (of a cohort of 2,950 men aged 62 to 91) had prostate cancer 1 . Note that the PSA assay is also used to monitor the development of prostate cancer.
The biopsy is not devoid of adverse effects. The most common are the presence for a very short time of blood in the urine, stool or semen, fever and infection of the prostate.
In practice :
- if the prostate is abnormal on digital rectal examination and its palpation suggests cancer, the biopsy is performed, even if the PSAs are normal;
- if the prostate is normal on palpation and the PSAs are greater than 4 ng/ml, the biopsy will be performed if the PSAs increase over time.
Its purpose is palpation of the prostate gland. To do this, the doctor inserts a gloved finger into the rectum and can thus estimate the volume and consistency of the prostate. This gesture allows only a partial appreciation. But it sometimes makes it possible to detect cancers in people who have a normal rate of prostate-specific antigen (= APS or PSA for “Prostatic Specific Antigen”).
It is only performed to perform a prostate biopsy and is of no interest alone.
Biopsy during transrectal ultrasound
During an ultrasound, the doctor can guide a needle to perform prostate biopsies, that is, to remove a little prostate tissue to have it examined under a microscope.
This allows the Gleason score to be quantified. Only a biopsy can definitively diagnose prostate cancer. The biopsy is usually performed using a needle inserted into the prostate.
From 10 to 12 tissue samples are taken during the same session, in different areas of the prostate. This technique is used for diagnostic purposes, not screening. This means that it is performed when a man has a high PSA or when digital rectal examination detects an abnormal prostate.