Prognostic significance of radiologic and histologic response to neoadjuvant chemotherapy in localized synovial sarcoma.

10578 Background: The role of neoadjuvant and adjuvant chemotherapy in localized synovial sarcoma (SS) is still controversial. Histologic response to neoadjuvant chemotherapy is an independent prognostic variable in bone sarcomas. Data regarding the prognostic value of response to noeadjuvant chemotherapy in STS are limited. Methods: 68 patients with localized STS, treated with neoadjuvant anthracycline/ifosfamide-based chemotherapy and assessable for response to chemotherapy were included prospectively in the French Sarcoma Group (GSF) database from 1985 to 2011. All the cases were reviewed by the pathology subcommittee of the GSF. Radiological response to chemotherapy was assessed according to RECIST criteria. Good response was defined as partial response or stable disease according to RECIST and ≤10% recognizable tumor cells in the surgical specimen. Poor response was defined as stable or progressive disease according to RECIST and ≥ 50% recognizable tumors cells in the surgical specimen. All the other...