sarcoma treatment and prognosismetastatic ewing sarcoma prognosisretroperitoneal sarcoma prognosismetastatic sarcoma prognosispleomorphic sarcoma prognosissarcoma cancer prognosisabdominal sarcoma prognosisbladder sarcoma prognosisuterine sarcoma prognosissynovial sarcoma prognosismyeloid sarcoma prognosismyxoid sarcoma prognosis