Outcome of patients with undifferentiated embryonal sarcoma of the liver treated according to European soft tissue sarcoma protocols.

Background: To assess the outcomes of pediatric patients with undifferentiated embryonal sarcoma of the liver (UESL) and treatment including at least surgery and systemic chemotherapy.

Methods: This study included patients aged up to 21 years with a pathological diagnosis of UESL prospectively enrolled from 1995 to 2016 in three European trials focusing on the effects of surgical margins, preoperative chemotherapy, use of radiotherapy (RT), and chemotherapy.

Results: Out of 65 patients with a median age at diagnosis of 8.7 years (0.6-20.8), 15 had T2 tumors, and one had lymph node spread, 14 were Intergroup Rhabdomyosarcoma Study (IRS) I, nine IRS II, 38 IRS III, and four IRS IV. Twenty-eight upfront surgeries resulted in five operative spillages and 11 infiltrated surgical margins, whereas 37 delayed surgeries resulted in no spillages (p = .0119) and three infiltrated margins (p = .0238). All patients received chemotherapy, including anthracyclines in 47. RT was administered in 15 patients. With a median follow-up of 78.6 months, 5-year overall and event-free survivals (EFS) were 90.1% (95% confidence interval [CI]: 79.2-95.5) and 89.1% (95% CI: 78.4-94.6), respectively. Two out four local relapses had previous infiltrated margins and two out of three patients with metastatic relapses received reduced doses of alkylating agents. Infiltrated margins (p = .1607), T2 stage (p = .3870), use of RT (p = .8731), and anthracycline-based chemotherapy (p = .1181) were not correlated with EFS.

Conclusions: Multimodal therapy improved the outcome of UESL. Neoadjuvant chemotherapy for pediatric patients increases the probability of complete surgical resection. The role of anthracyclines and RT for localized disease remains unclear.