Predictors of survival in dedifferentiated liposarcoma: A population-based analysis of the SEER database.

Dedifferentiated liposarcoma (DDLPS) represents a high-grade sarcoma characterized by transition from well-differentiated liposarcoma to non-lipogenic sarcoma. Population-based data examining prognostic factors and treatment outcomes remain limited. This study aimed to identify predictors of survival and evaluate treatment modalities in patients with DDLPS using the Surveillance, Epidemiology, and End Results database. We identified 3962 patients diagnosed with DDLPS between 2000 to 2022 from the Surveillance, Epidemiology, and End Results database. Patient demographics, tumor characteristics, treatment modalities, and survival outcomes were analyzed. Cox proportional hazards regression models were utilized to identify independent prognostic factors for overall survival (OS) and cancer-specific survival. The cohort had a median age of 66 years (interquartile range 57-75), with male predominance (67.5%). Primary tumors were predominantly located in soft tissues (51.4%) and retroperitoneum (36.1%). The median tumor size was 145mm (interquartile range 82-220 mm). Surgery was performed in 85.4% of patients, while radiation therapy and chemotherapy were administered to 33.5% and 18.2%, respectively. Median OS was 54.0 months with 1-year, 2-year, 3-year, and 5-year survival rates of 78.8% (95% confidence intervals [CIs]: 77.5-80.1%), 67.9% (95% CI: 66.4-69.4%), 59.6% (95% CI: 58.0-61.3%), and 47.6% (95% CI: 45.8-49.4%), respectively. In multivariate analysis including 1507 patients with complete staging data, independent predictors of worse OS included advanced age (hazard ratios [HR] = 1.42 per 10 years, 95% CI: 1.34-1.50, P < .0001), regional stage (HR = 1.30, 95% CI: 1.13-1.48, P < .05), distant stage (HR = 2.45, 95% CI: 2.02-2.97, P < .0001), and increasing tumor size (HR = 1.01 per cm, 95% CI: 1.01-1.01, P < .0001). Surgical resection conferred significant survival benefit (HR = 0.29, 95% CI: 0.23-0.36, P < .0001), as did radiation therapy (HR = 0.75, 95% CI: 0.66-0.86, P < .0001). Paradoxically, chemotherapy was associated with worse survival (HR = 1.42, 95% CI: 1.20-1.69, P < .0001). Retroperitoneal location demonstrated worse prognosis compared to non-retroperitoneal sites (median OS: 46.0 vs 60.0 months, log-rank P = .0001; median cancer-specific survival: 84.0 vs 122.0 months, log-rank P < .0001). This large population-based analysis demonstrates that surgical resection remains the cornerstone of treatment for DDLPS, providing substantial survival benefit. Advanced stage, older age, and larger tumor size independently predict poor outcomes. The adverse association with chemotherapy likely reflects selection bias, with systemic therapy reserved for aggressive or advanced disease.