What are the stages of Prostate Cancer ? 

Key Points
                    - After prostate cancer has been diagnosed, tests are done to find out if cancer cells have spread within the prostate or to other parts of the body.     - There are three ways that cancer spreads in the body.    - Cancer may spread from where it began to other parts of the body.    - The following stages are used for prostate cancer:         - Stage I     - Stage II     - Stage III     - Stage IV
                
                
                    After prostate cancer has been diagnosed, tests are done to find out if cancer cells have spread within the prostate or to other parts of the body.
                    The process used to find out if cancer has spread within the prostate or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The results of the tests used to diagnose prostate cancer are often also used to stage the disease. (See the General Information section.) In prostate cancer, staging tests may not be done unless the patient has symptoms or signs that the cancer has spread, such as bone pain, a high PSA level, or a high Gleason score.   The following tests and procedures also may be used in the staging process:         -   Bone scan : A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones and is detected by a scanner.     -   MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).    -   CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.    -   Pelvic lymphadenectomy : A surgical procedure to remove the lymph nodes in the pelvis. A pathologist views the tissue under a microscope to look for cancer cells.    -   Seminal vesicle biopsy : The removal of fluid from the seminal vesicles (glands that make semen) using a needle. A pathologist views the fluid under a microscope to look for cancer cells.    -   ProstaScint scan : A procedure to check for cancer that has spread from the prostate to other parts of the body, such as the lymph nodes. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material attaches to prostate cancer cells and is detected by a scanner. The radioactive material shows up as a bright spot on the picture in areas where there are a lot of prostate cancer cells.        The stage of the cancer is based on the results of the staging and diagnostic tests, including the prostate-specific antigen (PSA) test and the Gleason score. The tissue samples removed during the biopsy are used to find out the Gleason score. The Gleason score ranges from 2-10 and describes how different the cancer cells look from normal cells and how likely it is that the tumor will spread. The lower the number, the less likely the tumor is to spread.
                
                
                    There are three ways that cancer spreads in the body.
                    Cancer can spread through tissue, the lymph system, and the blood:         - Tissue. The cancer spreads from where it began by growing into nearby areas.     - Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.     - Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.
                
                
                    Cancer may spread from where it began to other parts of the body.
                    When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.         - Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.    - Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.        The metastatic tumor is the same type of cancer as the primary tumor. For example, if prostate cancer spreads to the bone, the cancer cells in the bone are actually prostate cancer cells. The disease is metastatic prostate cancer, not bone cancer.    Denosumab, a monoclonal antibody, may be used to prevent bone metastases.
                
                
                    The following stages are used for prostate cancer:
                    Stage I    In stage I, cancer is found in the prostate only. The cancer:             - is found by needle biopsy (done for a high PSA level) or in a small amount of tissue during surgery for other reasons (such as benign prostatic hyperplasia). The PSA level is lower than 10 and the Gleason score is 6 or lower; or     - is found in one-half or less of one lobe of the prostate. The PSA level is lower than 10 and the Gleason score is 6 or lower; or     - cannot be felt during a digital rectal exam and cannot be seen in imaging tests. Cancer is found in one-half or less of one lobe of the prostate. The PSA level and the Gleason score are not known.               Stage II    In stage II, cancer is more advanced than in stage I, but has not spread outside the prostate. Stage II is divided into stages IIA and IIB.    In stage IIA, cancer:            -  is found by needle biopsy (done for a high PSA level) or in a small amount of tissue during surgery for other reasons (such as benign prostatic hyperplasia). The PSA level is lower than 20 and the Gleason score is 7; or     -  is found by needle biopsy (done for a high PSA level) or in a small amount of tissue during surgery for other reasons (such as benign prostatic hyperplasia). The PSA level is at least 10 but lower than 20 and the Gleason score is 6 or lower; or     - is found in one-half or less of one lobe of the prostate. The PSA level is at least 10 but lower than 20 and the Gleason score is 6 or lower; or     - is found in one-half or less of one lobe of the prostate. The PSA level is lower than 20 and the Gleason score is 7; or     - is found in more than one-half of one lobe of the prostate.            In stage IIB, cancer:            - is found in opposite sides of the prostate. The PSA can be any level and the Gleason score can range from 2 to 10; or     - cannot be felt during a digital rectal exam and cannot be seen in imaging tests. The PSA level is 20 or higher and the Gleason score can range from 2 to 10; or     - cannot be felt during a digital rectal exam and cannot be seen in imaging tests. The PSA can be any level and the Gleason score is 8 or higher.              Stage III    In stage III, cancer has spread beyond the outer layer of the prostate and may have spread to the seminal vesicles. The PSA can be any level and the Gleason score can range from 2 to 10.       Stage IV    In stage IV, the PSA can be any level and the Gleason score can range from 2 to 10. Also, cancer:            - has spread beyond the seminal vesicles to nearby tissue or organs, such as the rectum, bladder, or pelvic wall; or      - may have spread to the seminal vesicles or to nearby tissue or organs, such as the rectum, bladder, or pelvic wall. Cancer has spread to nearby lymph nodes; or     - has spread to distant parts of the body, which may include lymph nodes or bones. Prostate cancer often spreads to the bones.