Stage and Grade of Prostate Cancer
Each type of cancer has its own unique system
for staging and grading. Stage describes how advanced a cancer is. Grade describes how much, or little, it looks
like normal tissue and how likely it is to spread. The stage and grade can help select the
treatment and predict the prognosis of the cancer.
Prostate Cancer Stage
Prostate cancer is staged by the tumor, node, and metastasis (TNM) staging system. Staging may be done using the digital rectal exam to check the feel of the prostate and imaging studies such as CT, MRI, or bone scan. It can also be done by looking at the prostate and lymph nodes under a microscope after they have been removed. The staging system for prostate cancer is described in the table below.
Tumor is completely inside the prostate and cannot be felt during digital rectal exam
Tumor is completely inside the prostate and can be felt during digital rectal exam
|T3 or T4||
Cancer has spread outside of the prostate
|N+ or M+||
Cancer has spread to the lymphnodes (N+), or the bones or other organs (M+)
Prostate Cancer Grade
The most common grading system for prostate cancer is the Gleason score. It is based on how the tissue sample looks and is made up of two different numbers. A pathologist looks at the tissue sample under a microscope and will see tumor patterns. They will assign a number to the most common pattern, and another number to the second most common pattern. The numbers range from 1 to 5. Grade 1 looks most like normal prostate tissue and grade 5 looks very different from normal prostate tissue. The numbers are added together to determine a Gleason score. For example 3+3=6. In this system it is uncommon to see scores less than 6. Gleason 6 cancers are called low grade, Gleason 7 are intermediate grade, and Gleason 8, 9, and 10 cancers are high grade.