Predictive factors of histological response to primary chemotherapy in Ewing's sarcoma.

Clinicopathologic variables associated with a good histological response to primary chemotherapy in Ewing's sarcoma are identified. The histological response to preoperative chemotherapy in 243 cases of Ewing's sarcoma treated with neoadjuvant chemotherapy was analyzed in relation to different clinicopathological features (sex and age of the patients, tumor size, serum lactate dehydrogenase (LDH) levels, tumor site) and to the type and schedule of anticancer drugs delivered preoperatively according to three consecutive chemotherapy regimens. A higher rate of good responses was achieved with the use of ifosfamide and dactinomycin in addition to a conventional three-drug VAC regimen, suggesting that these drugs should be included from the beginning in neoadjuvant regimens for the treatment of Ewing's sarcoma. The analysis of event-free survival in 158 patients with a 4-year minimum follow-up confirmed that histological response to preoperative chemotherapy is a reliable predictor of outcome in Ewing's sarcoma.