Prostate cancer is staged both by microscopic evaluation from a biopsy or prostate surgery, and by clinical exam and radiology studies (bone, CT, and/or PET scans).

Grade/Gleason score. To find your Gleason score, a pathologist will examine a sample of your prostate cancer cells under a microscope and assign it a number between 2 and 10. The lower your score, the less likely your cancer is to grow and spread rapidly. According to studies at the Prostate Cancer Research Institute in Los Angeles, a Gleason score is the best possible measure of how aggressive cancer cells are.

TNM level. Your pathologist will determine how extensive the disease is by using the TNM system, which stands for tumor (size), nodes (cancer present or not) and metastasis (cancer spread to distant organs). A number is assigned to each category. Once the TNM categories are determined, this info is combined with the grade to create an overall stage, from 0 for noninvasive to IV for the most invasive (see below). However, most commonly, clinicians will refer to the “T stage” as in “T1c,” which means the cancer was detected only because of an elevated PSA. More detail on staging can be found here.

Stages of prostate cancerI—Invasive: These cancers cannot be felt during a digital rectal exam (DRE) or seen with an imaging test. They are likely to grow slowly.

II—Invasive: These cancers can be felt during a DRE but have not spread beyond the prostate.

III—Invasive: These cancers have broken through the prostate capsule.

IV—Invasive: Metastatic (has spread to other parts of the body, such as the bladder, rectum, bones, liver, lungs or lymph nodes)

Review your pathology report and radiology studies (if any) with your healthcare provider to make sure you have a thorough understanding of your cancer. That will help you make the best treatment decisions and learn how to be a proactive member of your health team.