Primary mesenteric sarcomas: Collaborative experience from the Trans-Atlantic Australasian Retroperitoneal Sarcoma Working Group (TARPSWG).

Background: Primary mesenteric soft tissue sarcomas (STS) are rare and limited evidence is available to inform management. Surgical resection is challenging due to the proximity of vital structures and a need to preserve enteric function.

Objectives: To determine the overall survival (OS) and recurrence-free survival (RFS) for patients undergoing primary resection for mesenteric STS.

Methods: The Trans-Atlantic Australasian Retroperitoneal Sarcoma Working Group (TARPSWG) is an intercontinental collaborative comprising specialist sarcoma centers. Data were collected retrospectively for all patients with mesenteric STS undergoing primary resection between 2000 and 2019.

Results: Fifty-six cases from 15 institutions were included. The spectrum of pathology was similar to the retroperitoneum, although of a higher grade. R0/R1 resection was achieved in 87%. Median OS was 56 months. OS was significantly shorter in higher-grade tumors (p = .018) and extensive resection (p < .001). No significant association between OS and resection margin or tumor size was detected. Rates of local recurrence (LR) and distant metastases (DM) at 5 years were 60% and 41%, respectively. Liver metastases were common (60%), reflecting portal drainage of the mesentery.

Conclusion: Primary mesenteric sarcoma is rare, with a modest survival rate. LR and DM are frequent events. Liver metastases are common, highlighting the need for surveillance imaging.