11054 Background: Large, high-grade extremity/trunk (ET) non-rhabdomyosarcoma soft-tissue sarcoma (STS) is at high risk for distant recurrence and death. The integration of chemotherapy (C) to standard of care neoadjuvant radiotherapy (RT) remains controversial, even for these patients. This study examines the impact of adding C to neoadjuvant RT on overall survival (OS) in high risk ET-STS. Methods: The National Cancer Data Base (NCDB) was queried for patients ≥18 years with high risk (≥5 cm + high grade) non-rhabdomyosarcoma ET-STS (WHO histology) who received neoadjuvant RT and limb sparing surgery from 2006-2014. Patients were next stratified based upon receipt of C (RT and CRT cohorts). Overall survival (OS) for RT vs CRT cohorts was analyzed using the Kaplan-Meier (KM) method, log-rank test, and Cox proportional hazards models. Propensity score-matched analysis (PSM) was employed to account for potential treatment selection bias between cohorts. Results: A total of 848 (71.1%) and 344 (28.9%) patients received RT and CRT, respectively. Patient cohorts were well-balanced except for the CRT cohort having higher rates of treatment in the West (22.1% vs 10.6%) & Midwest (28.3% vs 22.7%), Charlson-Deyo [CD] score 0 vs ≥1 (85.5% vs 79.4%), younger age (≤50) (45.9% vs 21.7%), synovial sarcoma histology (18.9% vs 3.2%), earlier year of diagnosis (2006-2010) (39.5% vs 32.3%), and positive lymphovascular invasion (2.0 vs 1.51%), (p < 0.05 each). The KM 5-year OS was significantly higher in the CRT vs RT cohort: 69.2% vs 58.1% on univariate (p < 0.0001) and multivariate analysis (Hazard Ratio [HR]: 0.66; 95% Confidence Interval [CI]: 0.52-0.85; p = 0.001) even after adjusting for age, race, income, CD score, histology, tumor size, tumor grade, and primary site (lower extremity; upper extremity; trunk). PSM identified evenly matched cohorts of 300 patients each with respect to age, income, CD score, histology, grade, tumor size, and primary site. The addition of neoadjuvant C remained prognostic for OS on PSM (HR: 0.74 [0.56-0.99], p = 0.042). Conclusions: The addition of C to neoadjuvant RT was associated with improved OS in patients with high risk non-rhabdomyosarcoma ET-STS in the NCDB. These hypothesis generating results support prospective evaluation.
PV-0048: Prognostic impact of tumor size and response in neoadjuvant radiotherapy of soft tissue sarcoma
