Staging is one way of organizing the information obtained from the prostate biopsy and staging tests that have been previously described to determine the overall stage of your prostate cancer. Knowing the stage of the cancer helps determine the best treatment option. The TNM classification system is the most commonly used system to describe the extent of cancer spread:

T (the extent of the prostate cancer)
N (the absence or presence of prostate cancer spread to lymph nodes)
M (the absence or presence of distant metastasis)

The purpose of staging is to determine the size and location of the tumor, whether it has spread beyond the prostate gland, and the characteristics of the prostate cancer cells. Various tests are available to appropriately identify the stage of prostate cancer.

Gleason Score

A specialized doctor called a pathologist examines prostate cancer cells under a microscope and assigns a number (grade) depending on how much the cells mimic the patterns of normal prostate cells. The Gleason score, which ranges from 2-10, is a sum of the grades of the two most common patterns seen under the microscope.

A high score is an indication of aggressive prostate cancer, which is likely to grow quickly and spread. Thus, a patient having a Gleason score of 8 has a significantly more aggressive tumor, as compared to a patient having a score of 4 or 5.