Low Survival Rates for Pediatric Patients with Tumor Thrombus in Sarcoma.

Background/Objectives: Tumor thrombus is an uncommon but serious finding in sarcoma, with limited pediatric data. While adult cases indicate a median survival of ~14 months, outcomes in children remain poorly understood. Methods: A retrospective review (1990-2025) was conducted at a single pediatric tertiary center. Patients <18 years with pathologically confirmed bone or soft tissue sarcoma and radiographic or histologic evidence of tumor thrombus were included. Minimum follow-up was 3 years or until end of life. The primary outcome was survival after tumor thrombus diagnosis. Results: Thirteen patients (nine males, four females) met the inclusion criteria. The median age at sarcoma diagnosis was 10.5 years. Osteosarcoma was the most common subtype (69.2%), with 76.9% of tumors arising in bone. Disease was localized in 53.8% and metastatic in 46.2% at presentation. Tumor thrombus was contiguous in 61.5% and noncontiguous in 38.5%. The median time from sarcoma diagnosis to death was 44.2 months; from tumor thrombus diagnosis to death, this was 15.2 months. The overall survival after tumor thrombus diagnosis was 30.8%. Conclusions: Pediatric sarcoma with tumor thrombus is associated with poor prognosis, and surgical intervention did not appear to result in long-term survival in this small series. Tumor thrombus may be noncontiguous from the primary tumor, emphasizing the importance of advanced imaging and its implications for treatment planning and counseling.