I am very sorry to hear about your Dad's diagnosis. While Stage 4 is very serious, there are treatments for it including chemotherapy and newer immunotherapy drugs. Much depends on his health, his age, etc. Please be sure that he gets an opinion from a National Cancer Institute-designated facility. These are cancer centers that have urologic oncology groups will be most knowledgable about current research and clinical trials. Even if there isn't a good treatment option for your dad, palliative care should be offered to ease any symptoms he has. You can find an NCI center near you at this link: https://www.cancer.gov/research/nci-role/cancer-centers