Interpreting your Gleason Grading Score for Prostate… Here’s How

Gleason Grade

Gleason Grading System - At lower grades, glandular strcture is comparatively more organized and differentiated whereas at higher grades, structure breaks down.

Dr. Donald Gleason, a pathologist, invented the Gleason Grading System in 1966, for evaluating the prognosis of men with prostate cancer. Gleason Score or Grade is the most widely accepted prostate cancer measurement that helps physicians determine severity of prostate cancer. Cancers with a lower Gleason score are less aggressive and have better prognosis when compared to those with higher scores.

What is Gleason Grading Score and Grade?

Gleason Grading System essentially looks at pattern of glands present in prostate. Tissue samples or biopsies are stained and studied under the microscope. Prostates that show very good differentiated glands are given low Gleason grades while those showing poor differentiation are given higher grades.

When a pathologist examines a prostate cancer specimen under the microscope, he tries to identify two types of patterns in the specimen and gives them each a Gleason Grade. The first pattern or primary pattern would be the most common pattern (more than 50% of total pattern seen) observed in the specimen. Second or secondary pattern is the next pattern that is observed which occurs in less than half of tissue (minimum of 5%) present in specimen. Grades allotted to each are added up to form Gleason Score or Gleason Sum.

Gleason Grade or Gleason Pattern Identification

The Gleason Grade is also known as the Gleason Pattern and ranges from 1 to 5:

  1. Gleason Grade 1 – Here, cancerous tissue is well differentiated and looks like normal prostate tissue. Glands are well packed and formed.
  2. Gleason Grade 2 – Here, well-formed large glands have more tissue between them.
  3. Gleason Grade 3 – Glands begin to look darker and show signs of randomness. They seem to be breaking away from monotony of their existence and invading surrounding tissue.
  4. Gleason Grade 4 – Majority of glands appear to be interspersed with surrounding tissue. A few recognizable glands are still present though.
  5. Gleason Grade 5 – There are no recognizable glands. Cells with distinct nuclei appear in sheets within surrounding tissue.

Interpreting the Gleason Score

Gleason Scores of 2 to 4 indicate less aggressive cancer while scores of 8 to 10 are indicative of highly aggressive forms of prostate cancer. Scores of 5, 6 suggest mild aggression while 7 is that of a moderately aggressive cancer. Sometimes, Gleason Score can be tricky, for example, a score of 3+4 and 4+3 both give 7. The thing to remember is that  first number is that of primary pattern and hence even though the Gleason Score is same, 4+3 indicates a far more aggressive form of cancer than 3+4. Hence, understanding breakdown of numbers is essential to imbibe the implication of Gleason Score.

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