Curability of Ewing's sarcoma and considerations for future therapeutic trials.

Abstract

Twenty previously untreated children with primary Ewing's sarcoma and 8 children with primary tumor and metastatic disease were treated with surgery or radiation therapy (6,000-7,000 rads) for their primary tumor and T-2 chemotherapy. Of the 20 children with primary Ewing's sarcoma treated with T-2 "adjuvant" chemotherapy, 15 had no evidence of recurrent disease for from 31+-82+ months (median 46+ months) from the start of treatment. The actuarial 5-year disease-free survival rate for this group of patients was 75%. Eight patients presenting with metastatic disease had complete responses to T-2 chemotherapy, but 7/8 with metastatic disease eventually had tumor recurrence. Examination of the treatment failures, both those patients relapsing after adjuvant chemotherapy for primary Ewing's sarcoma (5), and those relapsing after having a complete response of metastatic disease (7) to T-2 chemotherapy, revealed that all relapses occurred at the end of the second year of T-2 chemotherapy or after chemotherapy was stopped. In addition, of 23 patients receiving "curative" radiation therapy to their primary tumor, 5 had local recurrence (22%) and 6 (26%) had severe functional debility secondary to combined radiation therapy and T-2 chemotherapy. The conclusions drawn from this experience have led us to consider a new approach to the treatment of Ewing's sarcoma, namely: 1) more aggressive initial or "induction" chemotherapy with subsequent T-2 "maintenance" chemotherapy to eradicate more completely all metastatic microfoci of disease presumed to be present in patients with primary tumor at the time of diagnosis, and ostensively present in patients with metastatic disease; 2) the use of surgery alone or in combination with moderate doses of radiation therapy in those patients in whom we can predict a high frequency of local recurrence (pelvic lesions) or a high percentage of "functional failures" (young children with lower extremity lesions). Preliminary results with this latter approach are encouraging with 11/13 patients with primary Ewing's sarcoma free of disease at 12+-26+ months. A longer follow-up of this more aggressive treatment is needed to determine the superiority of this approach for both increased survival and improved late physical rehabilitation.