Curative management of retroperitoneal sarcoma relies on surgery, and complete monoblock resection is one of the main prognostic factors. The goal of this study was to search predictive factors for incomplete resection.

All patients undergoing surgery for retroperitoneal sarcoma in two University hospitals between 2010 and 202 were included. The main endpoint was incomplete resection (R1 ad R2) after surgery. Secondary analysis was performed where marginal R0 resection was considered as complete. Univariate and multivariable analysis of demographics, radiological, surgical and pathologic criteria were performed. Overall survival, local and distant recurrence were evaluated.

Fifty-eight patients were included in the study. Fifty patients had incomplete resection, of which seven had marginal R0 resection. In multivariable analysis, none of the factors analyzed were associated with incomplete resection. In secondary analysis, undifferentiated liposarcoma histology (OR 12.3, 95% CI [1.416–107.303], P=0.023) was statistically significantly associated with incomplete resection. Low grade (grade I) histology was predictive of complete resection (OR 0.24, 95% CI [0.060–0.959], P=0.043). Median follow-up duration was 27 months. Local and distant recurrence rates at three years were 37% and 22.4%, respectively.

In this study, we highlighted several predictive factors for incomplete resection. These factors enable us to define target populations that could most benefit from complementary therapy along with surgery.