Different subtypes of epithelioid sarcoma and their clinical implication: long-term multi-institutional experience with a rare sarcoma.

Epithelioid sarcoma (ES) is a very rare soft-tissue sarcoma with a high tendency of recurrence and metastasis. We analyzed clinical features of ES and aimed to identify the potential role of radio- and chemotherapy in ES. Fifty-five patients diagnosed with ES between 1997 and 2014 were enrolled from seven tertiary hospitals in Korean Cancer Research Group. The clinical variables were retrospectively reviewed and analyzed. Forty-six (84%) patients underwent surgical resection of ES, and among them, 27 experienced recurrence. In these patients, resection margin status and adjuvant radiotherapy were independent prognostic factors for longer recurrence-free survival (RFS), while adjuvant chemotherapy did not influence RFS. Twenty-two (40%) patients received palliative chemotherapy for metastatic or recurrent ES, and in these patients, palliative chemotherapy was the only independent prognostic factor for longer overall survival. Intriguingly, the clinical benefit of radio- and chemotherapy was observable only in proximal ES, but not in extremity ES, indicating that subtypes of ES might respond to radio- or chemotherapy differently. Proximal ES seems to benefits more from active anticancer treatment than conventional extremity ES. The aggressive characteristics of proximal ES could be overcome with an optimal multimodal treatment.