Gleason score
Encyclopedia
Prognosis
Prognosis is a medical term to describe the likely outcome of an illness.When applied to large statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe septic shock will die within 28 days" can be made with some confidence, because...
of men with prostate cancer
Prostate cancer
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...
. Together with other parameters, it is incorporated into a strategy of prostate cancer staging
Prostate cancer staging
Prostate cancer staging is the process by which physicians categorize the risk of cancer having spread beyond the prostate, or equivalently, the probability of being cured with local therapies such as surgery or radiation. Once patients are placed in prognostic categories, this information can...
which predicts prognosis and helps guide therapy. A Gleason score is given to prostate
Prostate
The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....
cancer based upon its microscopic
Microscopic
The microscopic scale is the scale of size or length used to describe objects smaller than those that can easily be seen by the naked eye and which require a lens or microscope to see them clearly.-History:...
appearance. Cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
s with a higher Gleason score are more aggressive and have a worse prognosis.
Process
Most often, a urologist or radiologist will remove a cylindrical sample (biopsyBiopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...
) of prostate tissue through the rectum
Rectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
, using hollow needles, and prepare microscope slides. After a prostate is removed in surgery, a pathologist will slice the prostate for a final examination.
Grades and scores
The pathologist assigns a grade to the most common tumorTumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
pattern, and a second grade to the next most common tumor pattern. The two grades are added together to get a Gleason Score. For example, if the most common tumor pattern was grade 3, and the next most common tumor pattern was grade 4, the Gleason Score would be 3+4 = 7. The Gleason Grade is also known as the Gleason Pattern, and the Gleason Score is also known as the Gleason Sum. The Gleason Grade or Gleason Pattern ranges from 1 to 5, with 5 having the worst prognosis. The Gleason Score ranges from 2 to 10, with 10 having the worst prognosis. For Gleason Score 7, a Gleason 4+3 is a more aggressive cancer than a Gleason 3+4. Also, there is not really any difference between the aggressiveness of a Gleason Score 9 or 10 tumor.
Patterns 1 through 5
Gleason patterns are associated with the following features:- Pattern 1 - The cancerous prostate closely resembles normal prostate tissue. The glands are small, well-formed, and closely packed.
- Pattern 2 - The tissue still has well-formed glands, but they are larger and have more tissue between them.
- Pattern 3 - The tissue still has recognizable glands, but the cellsCell (biology)The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
are darker. At high magnificationMagnificationMagnification is the process of enlarging something only in appearance, not in physical size. This enlargement is quantified by a calculated number also called "magnification"...
, some of these cells have left the glands and are beginning to invade the surrounding tissue. - Pattern 4 - The tissue has few recognizable glands. Many cells are invading the surrounding tissue
- Pattern 5 - The tissue does not have recognizable glands. There are often just sheets of cells throughout the surrounding tissue.
In the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, prostate cancer of Gleason pattern 1 and 2 are almost never seen. Gleason pattern 3 is by far the most common.
Primary, secondary, and tertiary
A pathologist examines the biopsy specimen and attempts to give a score to the two patterns.- First called the primary grade, represents the majority of tumor (has to be greater than 50% of the total pattern seen).
- Second - a secondary grade - relates to the minority of the tumor (has to be less than 50%, but at least 5%, of the pattern of the total cancer observed).
These scores are then added to obtain the final Gleason score.
Increasingly, pathologists provide details of the "tertiary" component. This is where there is a small component of a third (generally more aggressive) pattern. So there could be a Gleason 3+4 with a tertiary component of pattern 5 - this would be considered to be more aggressive than a prostate cancer that was Gleason 3+4 with no tertiary pattern 5. Although it is debatable as to what the full extent the tertiary component has on the aggressiveness of a cancer.
History
The scoring system is named after Donald GleasonDonald Gleason
Donald F. Gleason, M.D., Ph.D. was an American physician and pathologist, best known for devising the "Gleason score" which predicts the aggressiveness of prostate cancer in patients...
, a pathologist at the Minneapolis Veterans Affairs Hospital who developed it with other colleagues at that facility in the 1960s. It remains an important tool.