Prostate cancer – Diagnosis and classification

Prostate cancer screening

PSA – measurable in a standard blood sample

As well as producing seminal fluid, the prostate secretes a molecule known as prostate-specific antigen, or PSA.
Quantities of up to 4 ng/ml of PSA in the blood are generally considered to be normal. Above that level, the physician is likely to request a second test to see whether the PSA content is increasing, and may also prescribe other additional examinations to determine the cause of the rise in the PSA count.
PSA tests are often recommended for men over the age of 50. Although a high PSA content is indicative of a functional disorder involving the prostate, it is not a reliable tool for diagnosing cancer.
Additional examinations are necessary in order to diagnose cancer.

Digital rectal examination

This examination is performed by a general practitioner during a normal consultation. The physician inserts a finger into the patient's rectum in order to feel the prostate. This is a quick, painless procedure.

Prostate biopsies

To determine whether a patient is suffering from prostate cancer, a biopsy is performed. This involves removing tiny fragments of prostate that are then analyzed in the laboratory in order to study the types of cell contained in the samples.
Before the examination is performed, the patient is given an enema (washing out the rectum with a liquid solution) and an antibiotic treatment. The examination lasts between 5 and 15 minutes and can be performed under local anesthetic.
Guided by an ultrasound scanner (with a probe inserted into the rectum) that produces an image of the prostate, the physician collects between 6 and 12 prostate fragments using a special needle inserted through the wall of the rectum.

Gleason score

The Gleason score is determined after analyzing prostate biopsies. There are five types of prostate cell: type 1 cells are normal and type 5 are those in which cancer is most advanced. The Gleason score is calculated by observing which of the cell types in the specimen are most numerous and adding them together.
The score ranges from 6 to 10, depending on the aggressiveness of the cancer, with 10 being the most aggressive form.
Degree of risk or aggressiveness, based on the Gleason score:

• 6 or 7: intermediate-risk cancer
• Between 8 and 10: high-risk cancer

The Gleason score is generally expressed as follows: Gleason 7 (3+4).
Concerning the figures in brackets, the first digit indicates the most numerous cell type in the biopsy specimens and the second digit is the second most numerous cell type.

Staging

When prostate cancer has been diagnosed, the diagnosis must be refined by performing a series of imaging examinations for the staging assessment. The purpose of the staging assessment is to accurately determine whether the cancer is localized (i.e. wholly contained within the prostate gland) or has spread.

Scan

This painless examination, which lasts between 10 and 15 minutes, uses X-rays to produce a very accurate image of the target area, in this case the abdomen and groin (abdominopelvic scan).
The scan will reveal whether the prostate* cancer* has remained within the gland or has instead reached the prostatic capsule (i.e. the membrane surrounding the prostate), the seminal vesicles (i.e. the glands located above the prostate that produce seminal fluid) or the lymph nodes.

Magnetic resonance imaging (MRI)

An MRI scan is similar to an X-ray scan except that it uses a magnetic field rather than rays. This examination provides a very accurate image of the body's soft tissue, allowing the physician to see whether the cancer has spread to any other organs.

Bone scintigraphy (bone scan)

This examination reveals whether a prostate cancer has reached the skeleton. Bone scintigraphy is a painless procedure in which a product is injected into the blood in order to reveal any bony metastases on the images subsequently produced.

Different stages of prostate cancer

The type of treatment prescribed for cancer is largely determined by the disease's stage of development. The following scale indicates the degree of progression of the prostate cancer, from least-advanced to most-advanced:

Prostate cancer stages T1, T2, T3, T4

Localized cancers:

• Stage T1: corresponds to a tumor not detectable by a digital rectal examination. Only a few cells are cancerous. The patient does not experience any symptoms of the disease.
• Stage T2: corresponds to a cancer that is detectable by a digital rectal examination (a hard lump can be felt) and appears to be fully contained within the gland, whether in both lobes of the prostate or just one.

Advanced cancers:

• Stage T3: corresponds to a cancer that extends beyond the prostate and/or seminal vesicles.
• Stage T4: corresponds to a cancer that has spread to other organs near the prostate (such as the bladder and/or rectum).

 

 

Last update 1 June 2010.