Purpose of the study: Prognosis is generally considered poor for patients with an iliac bone localization of Ewing sarcoma because the deep tumor is often large with initial metastases. This study demonstrates that the predictive value of these factors is related to treatment and that early en bloc resection can modify the prognosis.

Material and method: We have treated 62 cases of Ewing tumor of the iliac bone since 1976, 36 males and 25 females, mean age 16.5 years (range 4 – 47). Thirteen patients presented primary metastases. Mean tumor size, measured by digital imaging, was 729 cm3. Adapted chemotherapy was given in all cases. Local treatment included exclusive radiotherapy in 20 patients, radiochemotherapy in 15 and exclusive en bloc extratumoral resection in 27.

Results: At 15 years mean follow-up, overall relapse-free survival at ten years was 38%. This rate was 43% among patients without metastasis and 18% for those with initial metastasis (the three other patients underwent surgical resection of a primary focus and a bone metastasis). For patients with localized disease, prognosis was essentially determined by type and timing of local treatment. Surgical resection did not appear to have a significant effect on prognosis for patients operated on after three months; for these patients, only those with total histological response survived. Conversely, patient who underwent surgery before three months with en bloc resection and chemotherapy with at least five drugs had a relapse-free survival of 80% at ten years.

Conclusion: The prognosis of Ewing sarcoma is seriously dependent on the therapeutic modality, even when the localization is known to have a poor prognosis such as the iliac bone. Early en bloc extratumoral resection (before three months) greatly improved the prognosis of patients without metastasis, even for those with a very large tumor. Conversely, prognosis remained very poor for patients given exclusive radiotherapy or operated on late.