Understanding Your Gleason Score and Prostate Cancer Risk
What is a Gleason Score?
If you have been diagnosed with prostate cancer, you very likely will want to know your outlook and treatment plan as quickly as possible. Your Gleason score is an important factor in predicting the behavior of your cancer and determining your best course of treatment.
To confirm a prostate cancer diagnosis, a doctor will perform a biopsy, using needles to remove tiny tissue samples from your prostate that are then examined under a microscope in a laboratory. If the cells in your biopsy show cancer, they will be given a grade indicating how fast your tumor is likely to grow or spread, with 1 being almost normal and 5 being cancerous. Because your cancer may contain areas with different grades, the doctor will identify the two most common grades and add them together to come up with your combined score.
What Does My Gleason Score Mean?
A combined Gleason score of less than 6 means your cancer is less aggressive and likely to grow slowly, while a combined score of 6 or 7 means it is likely to grow but may not spread quickly. A score of 8-10 indicates aggressive cancer. It is important to know that the first number assigned is the grade that is most common in the tumor. Therefore, a combined Gleason score of 4+3 indicates a more aggressive cancer than a score of 3+4.
What Other Factors Are Important in Determining My Prostate Cancer Risk?
When making your treatment decision, there are some additional factors to consider along with your Gleason score. These include blood PSA level, findings on your rectal exam, results of imaging tests, number of biopsy samples that contain cancer, how much of each tissue sample is made up of cancer, whether cancer has spread beyond the prostate, and whether cancer is found on both sides of the prostate.
How Reliable is My Gleason Score?
Your Gleason score usually reflects your cancer’s true grade, since it is based on samples from different parts of your prostate. However, about 20% of the time, the biopsy grade is lower than the true grade of your tumor because the biopsy misses a more aggressive area of the tumor. The opposite can also be true, with the true grade of the tumor being lower than what is seen on biopsy.
How Can I know if My Prostate Cancer is Really Low-Risk?
If you have been recently diagnosed with clinically low-risk prostate cancer (Gleason score of 3+4 or less than 7), you may be eligible for the Oncotype DX Genomic Prostate Score (GPS) test, which is designed to help you and your doctor make a more confident decision about your treatment plan. The test looks at the activity of certain genes in your tumor to help clarify the risk level of your cancer, as well as to determine whether you are likely to die or have your cancer spread within 10 years after surgery. With a more complete picture of your personal risk in hand, you can make a better decision about what treatment to pursue – active surveillance or aggressive treatment.
1 Cooperberg. 2010. JCO