Individual risk evaluation for local recurrence and distant metastasis in Ewing sarcoma: A multistate model: A multistate model for Ewing sarcoma.

Disease extent and histological response are risk factors for progression to DM or death. Tumor site and surgical margins are risk factors for LR. If disease progression occurs, previous risk factors lose their relevance. In case of isolated LR, time to recurrence is important for decision-making. Radiotherapy seems protective for LR especially in pelvic/axial. Low percentages of LR in extremity tumors and associated toxicity question the need for radiotherapy in extremity Ewing sarcoma.