What does the Gleason score mean?
The malignancy of the prostate carcinoma depends not only on the type and extent of the tumour but also on the extent to which the cells of the tumour tissue differ from the healthy prostate cells. The Gleason score is a measure of the extent and degree of tissue alteration. The higher the score, the more aggressive the tumour is.
How is the Gleason score determined?
To determine the Gleason score, several tissue samples (biopsies) are first taken from the prostate and examined microscopically by the pathologist. Five "growth patterns" are distinguished based on the shape and arrangement of the prostate cells. 1 stands for well differentiated; the tumor tissue is still very similar to the healthy tissue. In a 5, the tissue has already become widely de-differentiated and is only insignificantly similar to the original tissue, if at all. There is a high degree of malignancy.
|1||Glands uniform, medium sized and densely packed|
|2||Uneven glands, loose arrangement|
|Glands irregular, infiltration of peripheral cells|
|4||Fused glands, blurred tumor area|
|5||No clear glands, blurred tumor area, further changes|
How is the Gleason score composed?
Since tumour tissue is usually not homogeneous, two cell patterns are always assessed: The first number in the Gleason score indicates the cell pattern most frequently found in the tumour. The second number describes either the second most frequent or the most malignant pattern in this tumor area. The maximum Gleason score is 5+5=10 and the lowest today is 3+3=6. A tumour is only classified as clearly malignant if the Gleason score is 6 (3+3) or higher.
Clinical significance of the Gleason score
Low Risk: Prostate tumors with a Gleason score of 6 (3+3) are the most common with about 50 percent. They usually grow slowly. The formation of metastases in other organs and the infiltration of the prostate capsule are very rare.
Intermediate Risk: Tumours with a Gleason score of 7 (3+4 or 4+3) are classified as tumours with a medium risk.
High Risk: High risk tumors with a Gleason score of 8 (4+4), 9 (4+5 or 5+4) and 10 (5+5) are highly aggressive tumors. They grow rapidly and in many cases infiltrate prostate capsules and adjacent organs in the pelvis. They form early metastases in lymph nodes and bones.