Common Questions: The Prostate
What is prostate cancer grade? What is Gleason Score?
Grade is a measurement of the shape of prostate cancer cells. Prostate cancer grade is assigned by a pathologist reading a prostate biopsy. Prostate cancer grade informs us about prostate cancer behavior and prognosis. The more regular and round the cells, the less aggressive they are.
The most common form of prostate cancer grading is the Gleason grading system. The Gleason system relies on the detection of patterns of cell shape. Each type of prostate cancer cell shape is assigned a number from 1 to 5, as shown in the figure.
Given that prostate cancers are often composed of mixed populations of cell shapes, the Gleason system takes this partly into account. Specifically, the Gleason system requires that the most common cell shape be taken as the first of two grades; the second most common cell shape is taken as the second of two grades. The corresponding numbers, as assigned to the prostate cancer cell shapes by the pathologist, are added to give the Gleason Score. The Gleason Score ranges from 2 to 10, wherein the 2 is the least aggressive and the 10 is the most aggressive. The most common grade is Gleason score 6 (3 + 3).