A prostate biopsy may be recommended for men who have been diagnosed with an elevated PSA (Prostate Specific Antigen) level and an atypical digital rectal exam. During a biopsy, a thin needle is used to extract prostate tissue (or cores) from several locations within the prostate. These samples are evaluated by a pathologist who will determine if prostate cancer is present. If cancer cells are detected within a core, they will be assigned a Gleason score based on their appearance (normal to abnormal) and the cancer’s likelihood of spreading.
What is a Gleason score?
The Gleason Score was developed by American pathologist, Dr. Donald Gleason, in the mid-1960s. His system assigns a score of 1 through 5 to cancerous cells extracted during a prostate biopsy. Cells that appear to be nearly normal are scored as 1 or 2. The more abnormal the cells present, the higher the score (up to 5). To determine an overall Gleason score, the pathologist will add the scores from the two samples that contain the most cancer cells. As an example, if one core has a score of 5 and a second has a score of 4, the pathologist will combine the two scores of 5 + 4 to assign an overall score of 9. The placement of the first and second number is important because it indicates which cells are most common in the two isolated samples. In the previous example, the number 5 is placed first because the samples indicate more 5 grade cells and fewer 4 grade cells.
Understanding the Gleason score
During the initial evaluation, the pathologist will typically not include a score of 1 or 2 to be calculated into the final tally. Smaller scores indicate that the cells are low-grade or well differentiated, which means they are nearly normal, less aggressive, and are typically slow growing. Instead, the pathologist will look for cores with higher amounts of cancerous cells. Because of this, 6 is the lowest Gleason score assigned (3 + 3).
Men may also be given a Gleason score of 7, 8, 9 or 10. Scores between 8 and 10 indicate that cells are high-grade or poorly differentiated, which means they are irregularly formed, more aggressive and have the likelihood of spreading rapidly. Research has shown that cells identified with a Gleason score of 9 or 10 are two times more likely to spread compared to a score of 8.
Men who are assigned an overall score of 7 can have two different types of prostate cancer. Their Gleason score may be either a 3 + 4 = 7 or 4 + 3 = 7. As previously mentioned, the first number is indicative of cell appearance and aggressiveness. If the score begins with a 3, it means the cancer is better defined and slower growing than cells labeled as 4. In the first example (3 + 4), there are more cells identified as a 3. In the second example (4 + 3), there are more cells identified as 4, which are more irregular and likely more aggressive.
An individual’s Gleason score will help their doctor determine the best treatment options. If their score is low enough, the provider may recommend active surveillance. Higher scores will require different plans of action such as surgery, radiation or chemotherapy, among others.
While being a valuable diagnostic tool, the Gleason score is one of several factors that the provider will take into consideration when determining a treatment plan. The provider will also review the patient’s PSA level, their digital rectal exam, imaging, how many biopsy cores contained cancer and how extensive the cancer was in each core, if the cancer is known to have spread outside the prostate and if the cancer is present on both sides of the prostate gland.
It is important for men to schedule their prostate cancer screening, especially if they have a family history of prostate cancer. Contact the Urology Austin office closest to you to schedule your appointment.