The Gleason score is a system using to grade prostate cancer tissue which is dependent upon how it looks when analyzed under a microscope. The Gleason score ranges from two to ten and is an indicator of how likely it is that the cancer will spread. It also provides the doctor with the necessary information needed to select the most optimal treatment plan for the patient. Similar to staging prostate cancer, grade are given to each prostate cancer case to determine the severity of the disease. A urologist will assign a grade to the prostate cancer after the patient has undergone a prostate biopsy. The tissue samples are sent to a laboratory to be analyzed by a pathologist.

There are three categories for grading prostate cancer: Grade 1 means the cancerous tissue looks very much like normal prostate cells. Grades 2 to 4 means that some cells do look like normal prostate cells, others do not. Patterns of cells in these grades vary. Grade 5 means that the cells appear abnormal and do not look like normal prostate cells.

If the Gleason score is a 6 or lower, the tumor is in an early stage and the cancer is considered low-risk. This means that the prostate cancer is unlikely to grow or spread to other tissues or organs for many years. Men with low-risk prostate cancer are often monitored with active surveillance and have frequent checkups that may include PSA tests, DREs, ultrasound or other imaging, and repeat prostate biopsies.

If the Gleason score is a 7, the tumor is in between an early stage and an aggressive stage and the cancer is considered moderate-risk. While this means that the prostate cancer is unlikely to grow or spread for many years, the doctor will likely recommend treatment such as surgery or radiation while taking into account the patient’s age and overall health. Treating prostate cancer when the disease is in an early to medium stage gives the most optimal outcome.  

If the Gleason score is 8 or higher, the tumor is in a more advanced tumor stage and the cancer is considered high-risk. If the cancer has not spread beyond the prostate, it is still possible to treat it successfully which is usually done with surgery. Radiation may be required after surgery in case any prostate cancer cells may have escaped from the prostate gland due to being in an advanced stage. The doctor will likely recommend immediate treatment because high-risk prostate cancers are likely to grow or spread within a few years.