The Prostate Cancer Scale Explained

Prostate cancer is a type of cancer that develops in the prostate, the small, walnut-shaped gland in men that produces the seminal fluid that helps nourish and transport sperm. According to the U.S. Centers for Disease Control and Prevention (CDC), about 13% of American men will contract this type of cancer during their lifetime, and about two-thirds of these will die from it.

The Mayo Clinic explains that many prostate cancers are slow-growing and don't cause any serious problems. However, there are more aggressive types that can spread (metastasize) to other parts of the body quickly. Detecting prostate cancer when it is still confined to the prostate gland provides the best treatment outcome.

To determine how aggressive your prostate cancer is and how quickly it is likely to spread, doctors most commonly use the Gleason scale. This helps them formulate the best treatment plan for your individual case (per McMillan Cancer Support).

Mount Sinai explains that prostate cancer is diagnosed by looking at tissue samples under a microscope, which is referred to as a biopsy. The Gleason scale is used to indicate just how abnormal the cells are and how likely they are to spread. 

To grade them, a doctor uses a scale of 1 to 5. For example, a score of 1 means they look nearly normal in appearance. A score of 5, on the other hand, indicates that are extremely abnormal. Generally, prostate cancers contain cells with varying degrees of abnormality. A doctor will take the two most commonly appearing grades and add them together to get the Gleason score. The higher the total number, the more aggressive the cancer is.

Mount Sinai explains that the lowest score given to a tumor is 3 since anything below that is close to normal. Most cancers will have a Gleason score of 6 or 7.

The Mayo Clinic further clarifies that the lowest possible Gleason score, 2, would indicate nonaggressive cancer. However, the highest score, 10, would indicate a very aggressive cancer. Additionally, a score of 6 means you have a low-grade cancer, while a 7 would mean you have a medium-grade cancer. Scores of 8,9, or 10 are associated with high-grade cancer.

Healthline explains that the Gleason score is one factor that a doctor will look at to determine whether your cancer is aggressive. They will also look at your prostate-specific antigen (PSA) blood tests and your cancer stage. Aggressive prostate cancer is not considered to be curable. Treatment will be aimed at shrinking the tumor, keeping it from spreading and reducing any associated cancer symptoms. Treatments can include chemotherapy, immunotherapy, radiation therapy, hormone therapy, and bone treatments.

Informedhealth.org says that low-risk prostate cancer usually grows very slowly if it grows at all. This makes a strategy called "active surveillance" an appropriate alternative to surgery or other invasive treatments. In this case, the tumor can be monitored over time to see if it changes before any treatments are instituted. A low Gleason score would factor into whether you are considered to be low-risk (via National Library of Medicine).