The aim of the study is to improve the understanding of molecular mechanisms in the development and progression of musculoskeletal tumors. These tumors do have in general unfavorable prognosis and conventional treatments (e.g. surgery, radiotherapy or chemotherapy) could not enhance the prognosis of these patients during the last ten to fifteen years. Therefore the investigators chose a new way, as they try to identify markers on a genetic level, who ideally act as a basis to develop new treatment options.