Gleason score is a histopronostic score of prostate cancer. It is THE prognostic factor for prostate cancer. Prostate tissue consists of several components: glandular tissue, smooth muscle tissue and stromal tissue. Prostate cancer is an adenocarcinoma resulting from tumour transformation of the prostate glands.
Gleason score grades
Gleason score defines a graded classification from 1 to 5: grade 1 is thus practically identical to the normal gland and can only be distinguished by cellular modifications, grade 3 shows the appearance of small, almost joined, glands, and grade 5 a complete destruction of the glands and the presence only of tumoural cellular clusters. When several different tumour cells are present within the gland, the Gleason score is then the sum of the grades of the two most frequent tumour cells. It can thus range from 2 (i.e. 1 + 1) graded 1-1 to 10 (i.e. 5 + 5) graded 5-5 depending on the aggressiveness of the cancer (10 representing the most aggressive cancer).
Extra reading: Know-it-all on prostate