Undifferentiated Embryonal Sarcoma of the Liver in Children Versus Adults: A National Cancer Database Analysis (†)

SIMPLE SUMMARY: Undifferentiated embryonal sarcoma of the liver (UESL) is the third most common type of liver malignancy in the pediatric population, following hepatoblastoma and hepatocellular carcinoma. In comparison to children, UESL is an extremely rare malignancy in adults. Although historically treatment was limited to surgical resection and survival was poor, the combination of surgical treatment and chemotherapy recently has led to improved survival. We attempted to examine the characteristics and outcomes of children and adults with UESL in a contemporary U.S. cohort. We showed that children demonstrate favorable survival with multimodal treatment, while adults demonstrate inferior outcomes and future research endeavors should focus on refining currently available treatment modalities for adults with UESL. ABSTRACT: This study evaluates the clinicopathological characteristics and outcomes of children vs. adults with undifferentiated embryonal sarcoma of the liver (UESL). A retrospective analysis of 82 children (<18 years) and 41 adults (≥18 years) with UESL registered in the National Cancer Database between 2004–2015 was conducted. No between-group differences were observed regarding tumor size, metastasis, surgical treatment, margin status, and radiation. Children received chemotherapy more often than adults (92.7% vs. 65.9%; p < 0.001). Children demonstrated superior overall survival vs. adults (log-rank, p < 0.001) with 5-year rates of 84.4% vs. 48.2%, respectively. In multivariable Cox regression for all patients, adults demonstrated an increased risk of mortality compared to children (p < 0.001), while metastasis was associated with an increased (p = 0.02) and surgical treatment with a decreased (p = 0.001) risk of mortality. In multivariable Cox regression for surgically-treated patients, adulthood (p = 0.004) and margin-positive resection (p = 0.03) were independently associated with an increased risk of mortality. Multimodal treatment including complete surgical resection and chemotherapy results in long-term survival in most children with UESL. However, adults with UESL have poorer long-term survival that may reflect differences in disease biology and an opportunity to further refine currently available treatment schemas.