The prostate is a small gland that is part of the male reproductive system, and, according to the National Cancer Institute, its function is to produce and store part of the semen. When prostate cancer is diagnosed, it is assigned a stage, based on the size of the tumor and if, and how far, the cancer has spread. The stages of prostate cancer also help the doctor determine the best course of treatment. Most stages of cancer are numbered I through IV, but there are some treatment centers and hospitals that give the cancer a letter, such as A through D.
Stage 0
While not all medical facilities use stage 0 as a stage, the National Cancer Institute lists it within the cancer staging system. They state that in this stage, cancerous cells are present only in the few cells in which they began. In prostate cancer, they will have not yet formed a tumor.
Stage I or A
In stage I of prostate cancer, symptoms are barely present, which means by the time many are diagnosed, it is well beyond this stage. The cancer does not show on a sonogram, and cannot be felt during a rectal exam. The National Cancer Institute states that stage I prostate cancer is often found by chance, when other procedures are being performed, such as a benign prostate enlargement, or when blood tests reveal an elevated PSA (prostate specific-antigen) level.
Stage II or B
Prostate cancer that is in stage II still remains only in the prostate, and has not spread to any lymph nodes or other parts of the body. However, according to Werner-Francis Urology Associates in Maryland, the tumor is larger. It can usually now be felt during a rectal exam and seen on a sonogram. The American Cancer Society states that there are times in stage II prostate cancer where it still cannot be felt in a rectal exam or seen with a sonogram, but it is caught with a needle biopsy, which is often done in response to elevated PSA.
Stage III or C
In stage III, the prostate tumor has grown beyond the prostate, and invades nearby vessels, and possibly organs. It can be easily felt with a rectal exam, and also shows up on a sonogram or MRI. The National Cancer Institute reports that while it has moved to nearby organs or tissues, it still has not spread into the lymph nodes, or farther areas of the body.
Stage IV or D
In prostate cancer, stage IV is the most progressed. The tumor has well advanced in size and is now in organs nearby, such as the bladder and the pelvic wall. The American Cancer Society states that it has also spread to one, or more, lymph nodes. The National Cancer Institute reports that it can also have spread into the bones, although it will still be called "prostate cancer," because it is where the cancer cells originated.
