DIAGNOSIS - Gleason Score

The Gleason Grading system is used to help evaluate the prognosis of men with prostate cancer. Together with other parameters, it is incorporated into a strategy of prostate cancer staging which predicts prognosis and helps guide therapy. A Gleason score is given to prostate cancer based upon its microscopic appearance. Cancers 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 (biopsy) of prostate tissue through the rectum, 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 tumor 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.

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 grades 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 Gleason, 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.

REFERENCE

1.  "Male Genital Pathology". Retrieved 2009-05-13.
2. Manage Account - Modern Medicine
3. Gleason, D. F. (1977). "The Veteran's Administration Cooperative Urologic Research Group: histologic grading and clinical staging of prostatic carcinoma". In Tannenbaum, M.. Urologic Pathology: The Prostate. Philadelphia: Lea and Febiger. pp. 171–198. ISBN 0-8121-0546-X.