(P 306) PROGNOSTIC NUTRITIONAL INDEX PREDICTS MAJOR POSTOPERATIVE COMPLICATIONS IN RETROPERITONEAL SARCOMA: RESULTS FROM THE LATAMSARC COHORT

Objective: Retroperitoneal sarcomas (RPS) are rare malignancies requiring complex, often multivisceral surgical resections. Despite curative-intent procedures, postoperative morbidity remains high. Identifying preoperative risk factors is crucial for enhancing patient selection and perioperative care. The Prognostic Nutritional Index (PNI) is a simple immunonutritional biomarker that is increasingly recognized in oncologic surgery; however, its utility in RPS has not been firmly established.
To assess whether preoperative PNI is associated with major postoperative complications and survival outcomes in patients undergoing surgery for RPS.

Methods: A multicenter retrospective analysis was conducted, including 71 patients with histologically confirmed primary or recurrent RPS who underwent surgical treatment between January 2022 and December 2024 at Latin American centers participating in the LATAMSARC consortium. The optimal PNI cutoff to predict major complications was defined by ROC analysis using Youden’s index. Patients were stratified into two groups based on PNI: low (≤33.0) and high (>33.0). Associations with significant postoperative complications (Clavien-Dindo grade ≥ III) were assessed using multivariable logistic regression. Kaplan–Meier estimates were used to evaluate survival.

Results: The cohort included 53.5% males, with a median age of 53 years. The most frequent histology was liposarcoma (74.6%). Most patients underwent extended resections (49.3%) and multivisceral surgery (median 3 organs resected). The optimal PNI cutoff was 33.0 (AUC 0.899, 95% CI: 0.802–0.996). Major complications occurred in 12.7% of patients. Those with low PNI had a significantly higher complication rate (16.0% vs. 5.4%, p = 0.047). In multivariable analysis, low PNI remained independently associated with significant complications (OR 3.45, 95% CI: 1.01–11.79, p = 0.048). The median disease-free survival was 38.0 months (95% CI: 28.7–47.3), and the mean overall survival was 36.9 months (95% CI: 33.7–40.0).

Conclusion: A preoperative PNI ≤33.0 was independently associated with a threefold increase in the risk of major postoperative complications. This finding has practical implications for the perioperative care of RPS patients. However, low PNI was not significantly associated with worse overall or disease-free survival. PNI may represent a valuable, accessible tool to guide perioperative decision-making and individualized optimization strategies in retroperitoneal sarcoma surgery.

Table 1. Demographic characteristics of the 71 patients included in the LATAMSARC cohort