This phase III trial compares the effect of adding chemotherapy (doxorubicin or epirubicin hydrochloride [epirubicin] with ifosfamide or dacarbazine) before standard surgery versus surgery alone in improving long-term survival in patients with retroperitoneal sarcomas that are able to be removed by surgery (resectable). Chemotherapy drugs, such as doxorubicin, epirubicin, ifosfamide, and dacarbazine, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving chemotherapy before surgery may make the tumor smaller and easier to remove and may increase patient survival, compared to surgery alone.