Modern multimodality management of patients with caval leiomyosarcoma: New treatment paradigms and potential molecular insights.

BACKGROUND AND OBJECTIVES Caval leiomyosarcomas (cLMS) are rare soft tissue sarcomas historically associated with high recurrence rates and poor prognosis. While radical resection remains the mainstay of therapy for cLMS, new systemic therapies have presented opportunities for multimodality treatment. We examined the clinical outcomes of patients with cLMS treated with modern, multimodality approaches, and compared their outcomes to those of patients with noncaval retroperitoneal LMS (ncLMS). METHODS A retrospective, single-institution review identified all patients diagnosed with primary retroperitoneal LMS from 2012 to 2018. Radiographic and pathologic review distinguished patients with cLMS and ncLMS. Standard clinicopathologic variables and response to chemotherapy (when applicable) were analyzed. Primary endpoints were overall (OS) and progression-free survival (PFS). RESULTS Eleven patients with cLMS were identified. Median tumor size was 7.5 cm (IQR, 5.0-14.3 cm); all patients had Stage II/III disease. Seven patients received neoadjuvant chemotherapy. Nine cLMS patients underwent R0/R1 resection; two did not complete resection. Six patients received adjuvant systemic therapy. Twenty patients with ncLMS were treated during the same period. No statistical intergroup differences were noted in tumor size, pathologic grade, stage, or resection margin status. Patients with ncLMS were less likely to receive neoadjuvant (10% vs. 64%) and adjuvant chemotherapy (30% vs. 55%). Two-year OS (81% vs. 78%; p = NS) and PFS (55% vs. 46%; p = NS) were comparable between cLMS and ncLMS patients. CONCLUSIONS Multimodality treatment with systemic therapy and aggressive surgical resection may achieve equivalent survival outcomes for patients with cLMS versus similar ncLMS. We recommend that all patients with cLMS be evaluated for multidisciplinary treatment. Genomic and proteomic expression profiling may identify novel or targetable mutations.