Thought I would share this with the board about
the Gleason score. Found it to be informative without being too technical. Taken from John Hopkins web site:
If you have had prostate cancer, you probably know that the Gleason score is the most important factor in predicting your current state of prostate cancer and its probable outcome. The score is based on tumor grade -- an indication of the tumor's aggressiveness. Tumor grade reflects how far the cancer cells deviate from normal, healthy cells.
Normal cells are highly organized, with well-defined structures. Cancer cells, in contrast, display various degrees of disorganization and distortion. Cancers whose cells appear closest to normal are considered grade 1 and generally are the least aggressive; those with highly irregular, disorganized features are classified as grade 5 and generally are the most aggressive.
The Gleason score is derived by determining the two most prevalent organizational patterns in the tumor, assigning each a grade and then adding the two numbers together. For example, if the most common pattern is grade 3 and the next most common pattern is grade 4, the Gleason score would be 3 + 4 = 7. Most pathologists do not recommend assigning Gleason scores below 5 based on needle biopsies because when the prostate is removed and the entire gland is evaluated, lower Gleason scores are almost always upgraded.
Most urologists would classify Gleason scores of 5 and 6 as low-grade tumors, a Gleason score of 7 as intermediate and Gleason scores of 8, 9 and 10 as high grade, with the least favorable outlook.
With the latest pathology techniques, it is sometimes possible to detect three different grades within the same biopsy. This can make deriving a Gleason score more complicated. A panel of international experts has recommended modifications in the grading system that account for these situations. These modifications are expected to be broadly adopted in the coming years.