Trends of lymph node sampling and metastasis in pediatric and young adult patients with clear cell, epithelioid, and synovial sarcomas.

Abstract

Clear cell sarcoma of soft tissue (CCS), epithelioid sarcoma, and synovial sarcoma are rare tumors historically identified as high risk for lymph node metastasis. This study investigates incident nodal metastasis and associated survival in children and young adults with these subtypes. Using the National Cancer Database (2004-2015), we created a retrospective cohort of 1303 patients (aged ≤25years) who underwent local control therapy for CCS, epithelioid sarcoma, and synovial sarcoma. Kaplan-Meier curves estimated overall survival (OS) by subtype. Stratifying on subtype, Cox regressions assessed OS by lymph node sampling status and nodal metastasis. There were 103 (7.9%) patients with CCS, 221 (17.0%) with epithelioid sarcoma, and 979 (75.1%) with synovial sarcoma. Lymph node sampling was more frequent in patients with CCS (56.3%) and epithelioid sarcoma (52.5%) versus synovial sarcoma (20.5%, p<.001). Synovial sarcoma metastasized to lymph nodes less frequently than CCS or epithelioid sarcoma (2.1% vs. 14.6% and 14.9%, p<.001). Across all subtypes, lymph node metastasis was associated with inferior OS (HR 2.02, CI 1.38-2.95, p<.001). Lymph node sampling was associated with improved OS in CCS (HR 0.35, CI: 0.15-0.78, p=.010), inferior OS in synovial sarcoma (HR 1.60, CI: 1.13-2.25, p=.007), and no statistical association with OS in epithelioid sarcoma. Lymph node metastasis is rare in children and young adults with synovial sarcoma. Lymph node sampling procedures were not consistently performed for patients with CCS or epithelioid sarcoma, but improved OS supports routine lymph node sampling in children and young adults with CCS.