Prostate cancer is the most common cancer in men in the UK. Over 40,000 men are diagnosed with prostate cancer every year and over 250,000 men are currently living with the disease. Normally the growth of all cells is carefully controlled in the body. As cells die, they are replaced in an orderly fashion. Cancer can develop when cells start to grow in an uncontrolled way. If this happens in the prostate gland, prostate cancer can develop. Most prostate cancer is slow-growing to start with and may never cause any problems or symptoms in a man’s lifetime. However, some men will have cancer that is more aggressive or ‘high risk.’ This needs treatment to help prevent or delay it spreading outside the prostate gland.