Sarcopenia After Neoadjuvant Radiation Is Associated With Increased Length of Stay Following Resection of Retroperitoneal Sarcoma.

BACKGROUND: Sarcopenia, defined as loss of muscle mass and function, has been identified as a negative prognostic factor in outcomes of major abdominal cancer operations. We sought to understand the impact of sarcopenia, using the psoas muscle index (PMI) as a surrogate, during neoadjuvant radiation (NR) on perioperative outcomes in patients with retroperitoneal sarcoma (RPS).

METHODS: We performed a single-institution retrospective review of patients with RPS undergoing resection between 2017 and 2024. Data were extracted for patient demographics, details of NR, surgical resection, length of stay (LOS), and 30-day postoperative complications (Clavien-Dindo Scale). PMI was defined as total psoas muscle area at the 3rd lumbar vertebrae divided by height squared, measured on preoperative imaging. PMI was stratified by quartile, and patients were evaluated for PMI loss during NR. Data were analyzed using Chi-square/Fisher's exact test for categorical variables, Student t-test/one-way ANOVA for continuous variables. Logistic regression model was built by backward elimination.

RESULTS: We identified 163 patients who underwent resection for RPS following NR and 51 of these had pre- and post-NR images available for review. Patients were 52.2% male, and 42.2% had at least one comorbidity (HTN, DM, or coronary artery disease). Subtype diagnoses included dedifferentiated liposarcoma (36.8%), well-differentiated liposarcoma (27.0%), leiomyosarcoma (18.4%), and other (17.8%). Lowest quartile PMI patients were older (71.2 vs. 59.5 years, p < 0.001) than highest quartile PMI patients, without differences in comorbidity rates (p = 0.747). Patients with PMI loss during NR did not have more (p = 0.291) or worse (p = 0.490) 30-day complications; however, after adjusting for covariates, lowest quartile PMI patients had significantly longer hospital LOS (8.8 vs. 6.4 days, p = 0.048) compared to those in the highest quartile.

CONCLUSIONS: In patients with RPS, sarcopenia is associated with longer hospital LOS. Loss of PMI during NR is an objective measure of poor radiation tolerance and is an independent variable that stratifies those at risk for a prolonged postoperative course. Prospective calculation of preoperative PMI can inform a targeted prehabilitation program or stratified ERAS pathways. Validation of these findings with larger, multi-institutional studies may significantly impact the perioperative cost of care.