Tumor on pelvic hip bone. had complete hip replacement. where might this cancer have started?

See an oncologist: Lung cancer, breast cancer, pancreatic cancers, etc, can metastasize to the bone. Multiple myeloma is also well known to cause lytic bone lesion. Solitary plasmacytoma can arise from a single bone area. Of course, there are primary bone cancers. If your pelvic bone biopsy showed invasive cancer, you should see an oncologist for a thorough work-up and treatment options.

Let me try to help: Pelvic bone tumor s are divided to primary tumors (started in the place we see them) or secondary move to the place we see them, many possibilities dose exists, check with your Doctor. The primary ones are not common and should be seen on the x-ray of the hips when they plan total hip replacements.