A story of continuing success—Radiotherapy for Ewing's Sarcoma

Abstract

Whereas the likelihood of 5-year survival among patients with Ewing’s sarcoma of bone at one time ranged from 5-10% recent reports show a marked improvement in prognosis and the reality of cure in the majority of those who present with localized disease.3”Vs However, the outlook for patients with wide spread and metastatic disease is much less optimistic. With the promising results emanating from combined modality treatment programs, attention must continually be given to the approach to the primary lesion, keeping in mind the primary goal of cure of the patient while maintaining maximal functional and cosmetic result. Thus, every patient with localized disease should be treated with curative intent with special attention and care given to the management of the primary lesion. Radiotherapy remains the standard therapy for primary Ewing’s sarcoma of bone. In this issue Dr. Perez and investigators from the Intergroup Ewing’s Sarcoma Study (IESS) provide a thoughtful and meticulous review of the importance of radiotherapy in the management of primary Ewing’s sarcoma of bone.3 This report includes much information and is important for careful review and data analysis. It provides an update of the role of radiation with an increase in patient numbers from previous Intergroup Ewing’s Sarcoma Study publications2.’ Thus this update is of merit, for as patient entry increases the impressive results from radiotherapy remain constant. The impact of cooperative group studies are evident when considering the therapeutic approaches to childhood cancer. Large groups such as IESS play an important role in pediatric malignancies because their observatioss and subsequent recommendations rapidly become policy among the therapeutic community. With rare tumors such as Ewing’s sarcoma we look to the cooperative groups for therapeutic guidelines. Yet we must continue to keep in mind the limitations of cooperative groups as well as their strengths of numbers. Multiinstitutional groups are only as good as their member constituency. Therefore, the evaluation, work-up, and details of therapy as well as the facilities, equipment, and individual expertise vary from institution to institution. Thus, we can anticipate that the therapeutic results from a large cooperative group such as the Intergroup Ewings Sarcoma Study could be obtained in a referral center specializing in pediatric cancer. Yet even in the IESS, which is remarkable for its strict guidelines and radiation quality control, data on greater than one-quarter of accessioned patients is not available for analysis. Of a total of 373 patients entered into the study up to November, 1978, 271 have been analyzed, leaving 102 who have had less than one year follow-up or in whom the radiotherapy records were not available for review. This high percentage of patients not yet evaluated could affect the results obtained, depending on the reasons why their radiotherapy records have not been analyzed. Several important observations are made by Dr. Perez et al. which merit comment. The impact of protocol violations becomes clear in the analysis of local recurrence, particularly among those patients who received less than adequate field size. In addition, the dose of radiation necessary for local control merits critical examination. It may well be, that in face of multi-agent chemotherapy, radiotherapy doses can be minimized from the range of 6000 rad or greater previously thought necessary for local control, to doses in the range of 4000 rad whole bone with boost to the primary bringing the tumor dose to 5000-5500 rad. The issue of adequate tumor volume has been much more controversial. However, IESS investigators now have provided clear evidence of increased local recurrence in patients who experience a minor field variation (I epiphysis not included) or major field variation (entire bone not irradiated or boost inadequate in volume). This underscores the early recommendations of Suit6 who recommended whole bone irradiation with serial cone down boosts to the area of primary bulk disease.