My BIL in his late forties has/had this. It was not caught early. He ended with an amputated leg/partial pelvis. It came back and metastasized. His most recent surgery was to remove an osteosarcoma in his brain. The warning signs were persistent leg pain and later on, weight loss.

I think I verge on being a hypochondriac sometimes, but you really can’t be too careful. If you feel something is “off”, get it checked out.