What’s a Gleason Score?

If you’ve never heard or understood what a Gleason score is, this article written by Jenna Fletcher and reviewed by Christina Chun, MPH, should help to enlighten you.

Those men diagnosed with prostate cancer want to know their outlook and treatment plan quickly.  The Gleason score will definitely play a major role in them deciding both of these issues.  Once a doctor diagnoses the cancer and a biopsy of the cells has been done, the Gleason score will be used to explain the results found.

Determining the aggressiveness of the cancer and the best course of treatment is how the Gleason score is also used.  This is a grading system that was discovered in the ‘60’s by a pathologist by the name of Donald Gleason.  He discovered that cancerous cells fall into 5 different patterns as they change from normal to tumorous cells.  They could be scored on a scale from 1 to 5.  Cells that have a 1 or 3 score are considered to be low-grade cells and tend to look similar to the normal cells.  Those cells that are closer to 5 are considered a high-grade and have mutated so much that they no longer look anything like a normal cell.

The biopsy result is what determines the Gleason score.  The doctor takes several tissue samples from different areas of the prostate, as cancer is not always present in all parts of the prostate.  They arrive at a Gleason sum by adding all the scores together to arrive at a combined score, or Gleason score.  The Gleason score is based on the two areas that make up most of the cancerous tissue.  The Gleason score is modified to reflect how aggressive the cancer is deemed when a biopsy sample has either a lot of high-grade cells or shows three different types of grades.

The Gleason score is between 2 and 10, but the higher the score does not always indicate the more aggressive cancer.  Usually the lower scores indicate a less aggressive cancer.  Most cases will score between 6 and 10.  Those that score 1 or 2 are not normally used because they aren’t usually the predominant areas of cancer.  A score of 6 is usually the lowest score possible and described as well-differentiated or low-grade, meaning the cancer is more likely to be a slowly growing and spreading cancer.  Those scores between 8 and 10 are referred to as poorly differentiated or high-grade and are likely to spread and grow quickly. The scores of 9 and 10 are twice as likely to grow and spread quickly as that of a score of 8.  A 7 score shows results in a couple ways.  Those of 3 + 4 have a good outlook where 4 + 3 is more likely to grow and spread.

There are additional considerations that include results of a rectal exam, the blood PSA level of the individual, results of imaging tests, the number of biopsy samples that contain cancer, whether the cancer has spread beyond the prostate, how much of each tissue sample is made up of cancer and whether cancer is found on both sides of the prostate.  There are also additional groupings called grade groups that help address some of the problems with the Gleason system.

One form of radiation therapy called Brachytherapy is where the radiation is administered to the prostate by placing small radioactive seeds directly into the prostate.  This is also referred to as internal radiation therapy.  The use of a machine that focuses beams of radiation onto the prostate from outside of the body is external beam radiation.

Patients with prostate cancer will need to discuss their treatment options with their doctor and decide which is the best treatment for them.

Dr Fredda Branyon