sarcoma treatment and prognosisretroperitoneal sarcoma prognosismetastatic sarcoma prognosisepithelioid sarcoma prognosispleomorphic sarcoma prognosissarcoma cancer prognosisabdominal sarcoma prognosisuterine sarcoma prognosissynovial sarcoma prognosismyeloid sarcoma prognosisewing sarcoma prognosismyxoid sarcoma prognosis