Prostate Screening
What is prostate cancer?
Prostate cancer is a type of cancer that develops in the cells of the prostate gland. For unknown reasons, one or more cells become abnormal. Eventually these cells may spread and invade normal tissues. They can grow through the capsule of the prostate gland and invade tissues outside the gland and then spread to other parts of the body through the lymphatic system. This system circulates throughout the body in much the same way that blood circulates. Lymph is a clear fluid that contains tissue waste products and immune system cells. Most of the lymph vessels of the prostate lead to pelvic lymph nodes. These nodes are often the first sites of spreading prostate cancer that is no longer curable. From there they can multiply and spread to other organs of the body.
Most prostate cancers grow very slowly. Autopsy studies show that many elderly men who died of other causes also had cancerous cells in their prostates that were never suspected. Doubling times of most prostate cancers average about 4 years. But some prostate cancers can grow and spread quickly.
Doctors speak of four stages of the disease. The first is the earliest stage when it cannot yet be felt by a digital rectal exam (DRE). The second is when it can be felt on a DRE but is still thought to be confined to the prostate. The third stage is when it has spread into adjacent tissues but has not yet reached the lymph nodes. The final stage is when the cancer has gotten into the lymph nodes or beyond.
