What do you suggest if my friend has osteosarcomas, is it cancer?

Yes. : Osteosarcoma is a cancer that originates in the bone. Not terribly common, are you sure that's what it is? I personally refer these patients to institutions where they can be seen by a multi-specialty team that includes a good pathologist who will review the biopsy and confirm the diagnosis. There are many good docs in Dallas including my Texas Oncology partners at Sammons and the folks at UTSW.