Demographics and clinical characteristics of epithelioid leiomyosarcoma: A National Cancer Database analysis.

Abstract

e23535 Background: Epithelioid leiomyosarcoma is a rare, aggressive variant of uterine leiomyosarcoma, defined by round-to-polygonal cells with eosinophilic cytoplasm. It demonstrates poorer survival than conventional leiomyosarcoma and limited response to chemotherapy and radiation. Due to its rarity, comprehensive epidemiological data remain limited. The demographics and clinical characteristics of patients with epithelioid leiomyosarcoma were analyzed using the National Cancer Database (NCDB). Methods: This retrospective cohort study queried the NCDB for patients with a histologically-confirmed diagnosis of epithelioid leiomyosarcoma between 2004-2020 (ICD-O-3 code 8891). Factors including age, sex, race, ethnicity, insurance status, facility type, treatment modalities, and survival outcomes were evaluated via descriptive statistics, regression analyses. Additional variables analyzed included treatment modalities, survival outcomes, and anatomical sites. Results: A total of 933 patients with epithelioid leiomyosarcoma were identified. Incidence showed a modest upward trend over the study period (R² = 0.36). Women were much more likely to be diagnosed (90.9%) compared to men, and the average age at diagnosis was 57 years. Most patients were non-Hispanic (88.5%), White (73.4%), lived in metropolitan areas exceeding one million residents (60.1%), and were privately insured (57.4%). The most common treatment facility type was an academic/research program (45.8%), followed by comprehensive community cancer programs (28.6%). Chemotherapy was the most frequently administered systemic treatment (41.2%), and surgery at the primary site was performed in 43.0% of cases. Mean tumor size was 109.94 mm, reflecting the aggressive nature of this malignancy. Survival analysis demonstrated two-year, five-year, and 10-year survival rates of 62.1%, 45.9%, and 35.6%, respectively, with a median survival of 90.5 months. Short-term mortality remained relatively low with 30-day and 90-day mortality rates of 1.5% and 3.9%, respectively. Conclusions: This is the first NCDB analysis of epithelioid leiomyosarcoma, providing novel characterization of socioeconomic and healthcare access factors in this patient population. These findings corroborate earlier reports that it predominantly affects women and frequently presents with large, aggressive tumors at the time of diagnosis. Patients are predominantly privately insured, reside in large metropolitan areas, and most commonly receive treatment at academic or research facilities. Despite relatively low short-term mortality rates, long-term survival remains poor, reflecting the aggressive nature of this malignancy. Future research is needed to better understand how demographic and socioeconomic factors influence diagnostic timing, treatment decisions, and survival outcomes in epithelioid leiomyosarcoma.