Prognostic factors in clear cell sarcoma: an analysis of soft tissue sarcoma in 43 cases

Clear cell sarcoma (CCS) of tendons and aponeuroses and CCS-like malignant gastrointestinal neuroectodermal tumor/sarcoma (GINET) are characterized by frequent local and distant relapses, alongside with low efficacy of all systemic treatments. We aimed to collect a comprehensive dataset to identify prognostic factors and treatment outcomes.

We performed a retrospective single center analysis for diagnosed CCS and GINET on demographic, tumor, treatment and survival data.

We identified 43 patients (w:25, m:18) with a median follow-up of 35mo and a 5y-OS-rate of 42%. At diagnosis the median age was 42yrs. Median tumor size was 3.6 cm (0.3-11.1 cm), and 24/26 (94%) tissues analyzed at our institute were EWSR1::ATF1-translocation-positive. Distant extremities (incl. knee or elbow) were affected in 72.5%. Of note, 79.5% received an excisional biopsy (benign histology suspected in 30.2%) leading to frequent incomplete resection. Final R0 status correlated significantly (p = 0.017) with longer survival rates compared to R + status in localized CCS (N0M0, 5-yr OS 0% vs 64%). Radiation and systemic treatment had limited antitumor effects while isolated limb perfusion was active in some patients. 18.6% of patients showed lymphatic spread and 20.9% distant metastases. Presence of initial M + was associated with a dismal survival of 1.4 years (M +) vs 7.1 years (M0; p < .001).

We here present one of the largest clinical cohorts of patients with CCS/GINET. Our data underscores the exceptional risk of metastatic disease even in small tumors. As systemic treatment and radiation showed limited efficacy, complete resection was the most important treatment option.