Prostate cancer is the most common non-skin cancer and second only to lung cancer in cancer-related deaths among men in the United States. Sometimes this cancer can be a small, slow-growing and present limited risk to the patient while at other times it can progress rapidly presenting great health risks. Yet, when prostate cancer is detected in its early stages, it can be effectively treated and cured. Therefore, it is advisable for men to have an annual medical check-up in order to examine their prostate's size, texture, and general functioning.The prostate is a part of the male reproductive system and is about the size and shape of a walnut, and is located between the bladder and the base of the penis. The urethra tube that carries urine from the bladder and semen from the sex glands out through the penis runs through the centre of the prostate. That is why any disease or condition that increases the size of the prostate or causes inflammation can lead to urinary problems as the enlarged prostate can squeeze the urethra thus affecting the flow of urine.One major function of the prostate is to lubricate the ejaculation process (by making and adding fluids to semen and other seminal fluids) and to increase the pH making the vagina more hospitable, and therefore more conducive for fertilization. It produces prostatic fluid when the man is aroused and contracts during ejaculation to empty.Normally body cells grow, divide, and produce more cells as needed to keep the body healthy. However, sometimes the process goes wrong when the cells become abnormal and form more cells in an uncontrolled way. These extra cells that form a mass of tissue are called a growth or tumour. Tumours can, however, be benign (not cancerous) or malignant (cancerous). Thus prostate cancer occurs when there is a malignant tumour which is formed in the tissue of the prostate. In its early stage, it needs the male hormone, testosterone to grow and survive.Also, sometimes, cancer cells break away from the malignant tumour in the prostate and enter the bloodstream or the lymphatic system and travel to other organs in the body. When cancer spreads from its original location in the prostate to another part of the body such as the bone, it is called metastatic prostate cancer, not bone cancer. Often the appearance of the cancer cell provides a clue to indicate if it is programmed to be slow-growing and relatively harmless or more aggressive and lethal.