The stage of your cancer is one of the most important factors in choosing the best way to treat it. Prostate cancer is staged based on the extent (how much the cancer has spread) of the cancer (using T, N, and M categories) and the PSA level and Gleason score (Grade Group) when it is first diagnosed.. For prostate cancers that haven’t spread (stages I to III), doctors also use risk groups …
https://www.cancer.org/cancer/prostate-cancer/treating/by-stage.html

