If your diagnostic tests show that you have a cancerous tumor, your doctor may want to determine the grade of the tumor. Grading is a measure of how aggressive the tumor is (that is, how fast it is likely to grow) and is based on the appearance of the cancer cells compared with normal tissue cells. Grading is done in a laboratory with cells taken from the prostate gland during biopsy.

The Gleason Grading System

One way of grading prostate cancer is to use the Gleason system, which assigns the numbers 1 through 5 to cancer cells based on their appearance compared to normal cells.

Cells that are similar to normal cells are likely to be slower growing, and they are assigned a low number. Cells that look different than normal cells are likely to be faster growing and thus are assigned a higher number.

Because prostate cancer tissue is often made up of areas that are very different from each other, the final Gleason score is the sum of the grades assigned to the two most commonly occurring cell patterns.

The final score is between 2 and 10 and describes the grade of the cancer as follows:

  • Grades 2-4: The cancer cells look similar to normal cells, and the cancer is likely to be less aggressive.
  • Grades 5-7: The cancer cells do not look like normal cells and are likely to be aggressive and grow faster.
  • Grades 8-10: The cancer cells are more likely to be very aggressive and to spread to other parts of the body.