3399936 RPLS retroperitoneal liposarcoma 52 3388745 RLPS retroperitoneal liposarcoma 36 1545569 RLS retroperitoneal liposarcoma 18 3830980 RPLPS Retroperitoneal liposarcoma 9 1556146 RPL retroperitoneal liposarcoma 8 392172 RL retroperitoneal leiomyosarcoma 3