Understanding Your Stage of Prostate Cancer

Stage is the word doctors use to communicate the size of a cancerous tumor and where and how far it has spread. The first place cancer is found in the body is called the primary site or primary tumor. When a cancer spreads to distant parts of the body, it's said to have metastasized. There are two types of stages of prostate cancer—clinical and pathological:

• The clinical stage helps your doctor decide on the best options for you. For prostate cancer, your clinical stage is determined from a digital rectal exam (DRE), biopsies, and any scans that are done, as well as your blood PSA level.

• The pathological stage is determined based on examination of your prostate after it is removed by surgery. Sometimes the pathological stage is higher because the tumor has spread more than what was expected during clinical staging.

How prostate cancer spreads

The first places that prostate cancer usually spreads are to nearby organs, such as your bladder, seminal vesicles (which produce some of the fluid in semen), rectum, and pelvis wall. Once cancer moves away from the prostate, it often goes into the nearby lymph nodes in your pelvis. In some cases, it spreads to distant parts of the body, mainly to the bones. The bones most often affected are the spine and ribs. In its later stages, prostate cancer may spread to the liver, lungs, bone marrow, or other lymph nodes. This is less common.

When prostate cancer has spread to another part of the body, it's not considered a new cancer. For instance, if prostate cancer spreads to the bones, it's not considered bone cancer. It's called metastatic prostate cancer.

There are also several kinds of cancer—such as kidney cancer—that can spread to your prostate. When this happens, the cancer is not called prostate cancer. This is because cancer is named for and treated based on the site of the original tumor. For example, if kidney cancer spreads to your prostate, it will be treated as metastatic kidney cancer, not as prostate cancer.

The stages of prostate cancer

Doctors need to know what stage your prostate cancer is in to decide what treatment options to recommend. The stage is based on the size and extent of your tumor, how far the cancer has spread, and your Gleason score (from the biopsy) and PSA level. Your oncologist gets this information from your DRE, biopsies, and scans. The most common way doctors describe the stage is with the TNM system.

The TNM System

The TNM System is a standard system for describing the extent of a cancer's growth. It is the most common system used to stage prostate cancer. It was developed by the International Union Against Cancer and the American Joint Committee on Cancer. Here's what the letters stand for in the TNM System:

• T refers to the size of the tumor in the prostate.

• N refers to whether the lymph nodes in the area of the prostate have become cancerous.

• M refers to whether the cancer has spread (metastasized) to other, distant organs in the body, such as your bones, liver, or lungs.

Your oncologist assigns numerical values from X to 3 to your T, N, and M stages. These letter and number combinations, along with your Gleason score and PSA level, are used to determine your overall disease stage.

Stage groupings of prostate cancer

Once the T, N, and M groups have been determined, they are combined (along with the Gleason score and PSA) in a process called stage grouping to yield an overall stage for the cancer. The stages are defined by Roman numbers I through IV. The lower the number, the less the cancer has spread. The higher the number, the more the cancer has spread. Be sure to ask your doctor to help explain your cancer's stage to you. 

Stage I

Either of the following applies:

The tumor can't be felt by DRE or seen on ultrasound but is discovered because of tests or surgery done for a different reason. It has not spread beyond the prostate. The Gleason score is 6 or less, and the PSA level is less than 10. (T1, N0, M0)

or

The tumor can be felt by DRE or seen on ultrasound, but it is confined to less than half of one side of the prostate. It has not spread beyond the prostate. The Gleason score is 6 or less, and the PSA level is less than 10. (T2a, N0, M0)

Stage IIA

One of the following applies:

The tumor can't be felt by DRE or seen on ultrasound but is discovered because of tests or surgery done for a different reason. It has not spread beyond the prostate. The Gleason score is 7, and the PSA level is less than 20. (T1, N0, M0)

or

The tumor can't be felt by DRE or seen on ultrasound but is discovered because of tests or surgery done for a different reason. It has not spread beyond the prostate. The Gleason score is 6 or less, and the PSA level is at least 10 but less than 20. (T1, N0, M0)

or

The tumor can be felt by DRE or seen on ultrasound, but it is confined to one side of the prostate. It has not spread beyond the prostate. The Gleason score is 7 or less, and the PSA level is less than 20. (T2a or T2b, N0, M0)

Stage IIB

One of the following applies:

The tumor can be felt by DRE or seen on ultrasound and is in both sides of the prostate. It has not spread beyond the prostate. The Gleason score and PSA can be any number. (T2c, N0, M0)

or

The tumor has not spread beyond the prostate. The PSA level is 20 or higher. The Gleason score can be any number. (T1 or T2, N0, M0)

or

The tumor has not spread beyond the prostate. The Gleason score is 8 or higher. The PSA can be any number. (T1 or T2, N0, M0)

Stage III

The tumor has spread outside of the prostate. It may involve some of the glands that produce semen, called the seminal vesicles. It has not spread to your lymph nodes or anywhere else in your body. The Gleason score and PSA can be any number. (T3, N0, M0)

Stage IV

One of the following applies:

The tumor has spread outside of the prostate and seminal vesicles and has reached nearby tissues such as the bladder's external sphincter (a muscle that helps control urination), rectum, and/or the wall of the pelvis. It has not spread to the lymph nodes or distant parts of the body. The Gleason score and PSA can be any number. (T4, N0, M0)

or

The cancer has spread to the lymph nodes, but it has not spread to distant parts of the body. The Gleason score and PSA can be any number. (Any T, N1, M0)

or

The cancer has spread to distant parts of the body. The Gleason score and PSA can be any number. (Any T, any N, M1)

Stages I and II are sometimes referred to as early-stage prostate cancer. Stages III and IV are sometimes called advanced prostate cancer.