The management of Ewing's sarcoma: role of radiotherapy in local tumor control.

The role of radiotherapy in the management of Ewing's sarcoma is discussed in view of both historical and current treatment policies. In particular, a comparison of radiotherapy and surgery as modalities for local control is presented. The technical aspects of dose and volume of radiotherapy are discussed together with its time relationship to chemotherapy and surgery. Although studies are in progress evaluating lower doses and smaller volumes than those used traditionally, until the results of these are available it would seem prudent to recommend the standard therapy as outlined in the guidelines of the recent Intergroup Ewing's Sarcoma Study Trial ( IESS -II). Recommended doses are: 4500 rad to the whole bone (except the contralateral epiphysis when the tumor is at or near the end of a long bone) plus a 5-cm margin around the tumor and any soft tissue extension, followed by 500 rad to a 5-cm margin, followed by 500 rad to a 1-cm margin given at 180-200 rad/day 5 days/week. Since many studies have shown it to be safe and possibly advantageous to postpone irradiation until induction chemotherapy has been completed, this appears to be the emerging approach. The value of partial excision (debulking) prior to irradiation is unclear at the present time. Radiotherapy may not be indicated for those patients with tumors of the lower limb when the unfused epiphyses would need to be irradiated. In addition, patients with pathologic fractures and with tumors of bones that are deemed expendable (such as ribs or clavicles) are probably best managed by complete surgical resection.