The prostate is the part of the male reproductive system. Its function is to add some of the secretions that make up the semen. It is a small chestnut-shaped organ made up of small glands and fibrous tissue and is located just below the bladder and in front of the rectum. Cancer is a disease in which abnormal cells in some organs or tissue go out of control, growing and increasing in number. Normal cells reproduce themselves throughout life, but in an orderly and controlled manner.
Normal growth occurs, worn out tissues are replaced and wounds heal.
When cells grow out of control and form a mass, the mass is called a tumor. Other tumors not only enlarge locally but also have the potential to invade and destroy the normal tissue around them and to spread to distant parts of the body. Such tumors are called malignant tumors, or cancer. Both prostate cancer and benign changes may cause difficulty with urination. Enlargement of the prostate caused by cancer or a benign change may put pressure on the urethra, the duct from which urine flows.