It depends on what type of cancer it is. It could be a slow or fast growing type or there might be more treatment options that could slow and decrease the tumor. You have to talk to your doctor and make decisions on treatment but the most important thing is comfort. If you have a treatment that extend your life but you are uncomfortable is it worth living and being so uncomfortable. Bone cancer can be very painful so make sure you tell your doctor you are hurting so he can adjust your medication there is so much out there and you should not be painful.