(P 402) LYMPH NODE METASTASES IN SOFT TISSUE SARCOMA: A DATABASE ANALYSIS

Objective: Certain soft tissue sarcomas (STS) metastasize to regional lymph nodes (LN). Proper identification of these metastases is relevant for staging and prognosis, as these portend a worse prognosis, and lymphadenectomy is associated with improved survival. Recent database studies have called into question the traditionally considered most prevalent STS subtypes with LN metastases, specifically synovial sarcoma. We aimed to analyze the largest STS patient cohort currently available to understand 1) prevalence of regional LN metastasis in STS, 2) factors associated with LN metastasis, and 3) implication of LN metastasis on survival.

Methods: We used the Surveillance, Epidemiology, and End Results (SEER) and National Cancer Database (NCDB) databases to identify patients with histologically confirmed diagnosis of STS located in the extremities, trunk, or pelvis. Duplicate patients were identified based on year of diagnosis, age, sex, race, tumor location, size, and histology. Demographic and clinical variables were assessed using descriptive statistics and overall survival was evaluated with the Kaplan-Meier method.

Results: In total, 65,538 patients with STS were included. Overall prevalence of regional LN metastasis (N1) on presentation was 3,066/65,538 (4.7%). The histologic subtypes with the greatest prevalence of N1 disease: rhabdomyosarcoma (26.2%), clear cell sarcoma (22.0%), epithelioid sarcoma (16.7%), angiosarcoma (10.8%), alveolar soft part sarcoma (10.6%). Prevalence of N1 spread in synovial sarcoma was 4.0%. Several tumor characteristics such as tumor grade, tumor size, stratified by histologic subtype, correlate positively with regional LN metastasis. Overall survival was significantly worse with LN and with distant metastatic spread.

Conclusion: This is the largest cohort to date to determine factors associated with LN metastasis in STS, which portends a worse prognosis. Limitations: database study design.

Soft tissue sarcoma (STS) histologic subtypes with regional lymph node (LN) metastasis