List of products in the National Drug Code with proprietary name . Leuprolide is used to treat advanced prostate cancer in men. It is not a cure. Most types of prostate cancer need the male hormone testosterone to grow and spread. Leuprolide works by reducing the amount of testosterone that the body makes. This helps slow or stop the growth of cancer cells and helps relieve symptoms such as painful/difficult urination. Talk to your doctor about the risks and benefits of treatment.