If prostate cancer is diagnosed, the doctor needs to know the stage
, or extent, of the disease to plan the best treatment. Staging is a careful attempt to find out whether the cancer has spread, and if so, to what parts of the body.
The Spreading of Cancer
There are three ways that cancer spreads in the body:
Cancer invades the surrounding normal tissue.
Through the lymph system.
Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
Through the blood.
Cancer invades the veins and capillaries and travels through the blood to other places in the body.
When cancer cells break away from the primary tumor and travel through the lymph or blood to other places in the body, another, or secondary tumor, may form. This process is called metastasis
. The secondary, or metastatic, tumor is the same type of cancer as the primary tumor. For example, if prostate cancer spreads to the bones, the cancer cells in the bones are actually prostate cancer cells. The disease is metastatic prostate cancer
, not bone cancer.
Stages of Prostate Cancer
The cancer can't be felt during a digital rectal exam, and it can't be seen on a sonogram. It's found by chance when surgery is done for another reason, usually for BPH. The cancer is only in the prostate. The grade is G1, or the Gleason score is no higher than 4.
The tumor is more advanced or a higher grade than Stage I, but the tumor doesn't extend beyond the prostate. It may be felt during a digital rectal exam, or it may be seen on a sonogram.
The tumor extends beyond the prostate. The tumor may have invaded the seminal vesicles, but cancer cells haven't spread to the lymph nodes.
The tumor may have invaded the bladder, rectum, or nearby structures (beyond the seminal vesicles). It may have spread to the lymph nodes, bones, or to other parts of the body.