Myeloablative radiochemotherapy and hematopoietic stem-cell rescue in poor-prognosis Ewing's sarcoma

The prognosis of patients with multifocal primary and early or multiple relapsed Ewing's sarcoma is poor with conventional chemoradiotherapy and surgery. We evaluated the efficacy and feasibility of a myeloablative regimen administered as consolidation treatment for these patients.

The ablative regimens consisted of simultaneous radiochemotherapy: 12 Gy hyperfractionated total-body irradiation (TBI; two doses of 1.5 Gy for 4 days) plus fractionated high-dose melphalan (30 to 45 mg/m2 for 4 days) followed by high-dose etoposide (40 to 60 mg/kg) with or without carboplatin (900 to 1,500 mg/m2) (hyper-ME +/- C). These regimens were applied in a dose-escalation study that included 17 patients. All patients underwent remission induction chemotherapy and local treatment before myeloablative therapy. Seven patients had multifocal primary Ewing's sarcoma, and 10 had early or multiple relapse. We performed a matched-cohort analysis of the 17 grafted patients with 41 historic controls matched for sex, age, diagnosis, extent of disease, interval from diagnosis to transplant in the transplant group, and interval from diagnosis to relapse in the control group.

The probability of relapse in the study patients is 52% at 6 years after the last event before transplantation. In the control group, the probability of relapse at 6 years was 98%. Eight of 17 treated patients are alive in complete remission at a median observation time of 49 months (range, 19 to 76) from the last event before transplantation. Probability of relapse-free survival in the study patients is 45% +/- 12% at 6 years after the last event before transplant, compared with 2% +/- 2% for the historic control group.

Myeloblative therapy with hyper-ME +/- C radiochemotherapy can improve the prognosis of multifocal primary and early or multiple relapsing Ewing's sarcoma.