Prostate cancer cells. Confocal light micrograph of metastasising (spreading) cancer cells (lower centre to lower right). The prostate gland is located at the base of the bladder. It stores and secretes seminal fluid. The causes of prostate cancer are not known, but it is more prevalent in men over 50 years of age. Metastatic cells are able to spread to other parts of the body. They usually do this through the lymph system. Once a cancer has spread the prognosis is often poor.