I have treated thousands of men with stage IV prostate cancer.
Stage IV prostate cancer can be painful secondary to the bone metastasis and and palliative radiation therapy can relieve the pain in most instances.
Androgen suppression (hormone therapy) is the mainstay of treatment for stage IV disease, but eventually it progresses despite being deprived of testosterone. Taxotere (if he can tolerate (fairly mild) chemotherapy) adds another 6 months or so to survival after it becomes androgen independent (also called “castrate resistant”). Newer drugs like abiraterone (Zytiga) can then add more time.
The latest drug that can be used to treat extensive bony metastasis is Radium-223 (Xofigo) which is also the first agent in a long time that prolongs survival.
Besides the bone, androgen independent prostate cancer occasionally spreads to visceral organs (I have treated men with spread to liver, bone and brain).
Men do not just die “with” stage IV prostate cancer, but frequently die OF it, and they deserve aggressive treatment, not only to improve their quality of life, but also to prolong their survival.