The grade refers to how the cancer cells look when compared to normal prostate cells. The grade of your cancer will help your healthcare provider predict how fast the cancer may grow and spread.

Prostate cancer is graded using the Gleason score. This scale uses numbers 1 to 5 to show how much the tissue (removed during the biopsy or surgery) looks like or does not look like normal prostate tissue. The grades are:

• Grade 1. The tissue with cancer cells looks a lot like normal prostate tissue.

• Grades 2 to 4. The tissue looks in between normal and very abnormal.

• Grade 5. The tissue looks very abnormal.

A grade is given to each of the 2 areas of the prostate that have the most cancer cells. The grades from the 2 areas are added together to give the Gleason score, which is between 2 and 10 (though scores below 6 are rarely used).

Gleason scores are:

• Gleason score of 6 or less. This is low-grade cancer.

• Gleason score of 7. This is intermediate-grade cancer.

• Gleason scores of 8 to 10. This is high-grade cancer.

The higher the Gleason score, the more likely the cancer will grow and spread.

In recent years, doctors have realized that the Gleason score might not always be the best way to grade prostate cancer. For example, not all cancers with a Gleason score of 7 are the same. Cancers with more Grade 3 areas (3 + 4 = 7 Gleason score) are less likely to grow and spread than cancers with more Grade 4 areas (4 + 3 = 7 Gleason score). Likewise, Gleason score 8 cancers are less likely to grow and spread than cancers with a Gleason score of 9 or 10. Because of this, doctors have started to use a newer system, which breaks up prostate cancers into 5 Grade Groups:

• Grade Group 1 = Gleason 6 (or less)

• Grade Group 2 = Gleason 3 + 4 = 7

• Grade Group 3 = Gleason 4 + 3 = 7

• Grade Group 4 = Gleason 8

• Grade Group 5 = Gleason 9 or 10

If your biopsy report shows you have prostate cancer, it might show both the Gleason score and the Grade Group.

The stage of your cancer describes how much it has spread. The most commonly used system to stage prostate cancer is the TNM system from the American Joint Committee on Cancer. 

The first step in staging is to find the value for each part of the TNM system. Here's what the letters stand for in the TNM system:

• T stands for tumor. This category notes the extent of the tumor inside the prostate and if it has spread into nearby areas.

• N stands for nodes. Lymph nodes are small collections of immune cells around the body. They help the body fight infections. This category notes if cancer cells have spread to the nearby lymph nodes.

• M stands for metastasis. This category notes if the cancer has spread to organs in other parts of the body. This may include a lung, your bones, liver, or brain. It also includes lymph nodes that are not near your prostate.

Numbers or letters after T, N, and M provide more details about each of these factors.

Two other factors are also important in determining the stage of prostate cancer:

• The blood PSA level at the time of diagnosis

• The grade group (Gleason score) of the cancer

Once your healthcare provider has determined your T, N, and M values, he or she then uses them, along with the PSA level and grade group of the cancer, to determine your overall stage grouping. A stage grouping can have a value of 1 to 4. These numbers are written as Roman numerals I, II, II, and IV. A stage grouping can have a value of 1 to 4. These numbers are written as Roman numerals I, II, II, and IV. The lower numbered stages mean cancers that are typically smaller and slower growing. So they tend to be easier to treat and cure. The higher the number, the more advanced the cancer is. Letters and numbers can be used after the Roman numeral to give more details.

These are the stage groupings of prostate cancer and what they mean:

Stage I. In this stage, one of the following is true:

• The tumor can't be felt by digital rectal exam (DRE) or seen on an ultrasound. (It was found due to tests or surgery done for another reason.) It has not spread beyond the prostate. The Gleason score is 6 or less. The PSA level is less than 10. (T1, N0, M0)

• The tumor can be felt by DRE or seen on ultrasound. It's in half or less than half of one side of the prostate. It has not spread beyond the prostate. The Grade Group is 1. The PSA level is less than 10. 

Stage II. This stage is divided into 3 sub-groups:

• Stage IIA. In this stage, one of the following is true:

  • The tumor can't be felt by digital rectal exam (DRE) or seen on an ultrasound. (It was found due to tests or surgery done for another reason.) It has not spread beyond the prostate. Grade Group is 1. The PSA level is between 10 and 20. 

  • The tumor can be felt by digital rectal exam (DRE) or seen on an ultrasound. (It was found due to tests or surgery done for another reason.) It's in in half or less than half of one side of the prostate and has not spread beyond the prostate. Or, the prostate was removed and the cancer was only inside it. The Grade Group is 1. The PSA level is between 10 and 20.

  • The tumor can be felt by DRE or seen on ultrasound. It's in more than half of one side of the prostate, or it's in both sides of the prostate. It has not spread beyond the prostate. Grade Group is 1. The PSA level is less than 20.

• Stage IIB. The tumor has not spread beyond the prostate. It may or may not felt by DRE or seen on ultrasound. The Grade Group is 2. The PSA level is less than 20.

• Stage IIC. The tumor has not spread beyond the prostate. It may or may not felt by DRE or seen on ultrasound. The Grade Group is 3. The PSA level is less than 20.

Stage III. This stage is divided into 3 sub-groups:

• Stage IIIA. The tumor has not spread beyond the prostate. It may or may not be felt by DRE or seen on ultrasound. The Grade Group is 1 to 4. The PSA level is 20 or higher.

• Stage IIIB. The tumor has spread beyond the prostate to the glands that make semen (seminal vesicles). Or, it has spread to nearby tissues such as the bladder's external sphincter muscle that controls urine flow, the bladder, the rectum, or the wall of the pelvis. It has not spread to nearby lymph nodes. The Grade Group is 1 to 4. The PSA can be any level.

• Stage IIIC. The tumor may or may not have spread beyond the prostate into nearby tissues. It has not spread to nearby lymph nodes. The Grade Group is 5. The PSA can be any level.

Stage IV. This stage is divided into 2 sub-groups:

• Stage IVA. The tumor may or may not have spread beyond the prostate into nearby tissues. It has spread to nearby lymph nodes, but it has not spread to other parts of the body. It's any Grade Group. The PSA can be any level.

• Stage IVB. The tumor may or may not have spread beyond the prostate into nearby tissues. It may or may not have spread to nearby lymph nodes. It has spread to other parts of the body, such as distant lymph nodes, bones, or other organs. It's any Grade Group. The PSA can be any level.

When your cancer is staged, your healthcare provider will talk with you about what the stage means for your treatment. Ask your healthcare provider to explain the stage of your cancer to you in a way you can understand. Ask any questions or talk about your concerns.