Prostate cancer stage IV refers to stage four prostate cancer, which is a common type of male reproductive organ tumor, particularly prevalent among elderly men. Stage four prostate cancer means that the tumor is not confined to the prostate and has already shown corresponding distant metastasis. The most common sites of metastasis for prostate cancer are the bones, followed by the lungs, liver, and others. When metastasis of prostate cancer occurs, it is considered to be at a late stage, and the primary treatments include endocrine therapy, chemotherapy, etc., with a poor prognosis.