An exploratory study of the potential clinical impact of ethnicity in patients with retroperitoneal sarcoma.

e23533 Background: Surgery is the mainstay of treatment for localized retroperitoneal sarcoma (RPS), but emerging data and interest support multimodality therapy, especially in the neoadjuvant setting. We studied the association of ethnicity with RPS outcomes and potential biases in non-surgical therapy utilization at an academic sarcoma referral center in a major U.S. city. Methods: Data were reviewed for all RPS patients under the care of a single sarcoma-trained surgical oncologist between July 2022 and December 2025. Inclusion criteria were: non-metastatic, primary disease; the most common RPS histologic types (liposarcoma, leiomyosarcoma, undifferentiated pleomorphic sarcoma, malignant peripheral nerve sheath tumor, solitary fibrous tumor); and curative-intent, complete resection (R0/R1). For study patients, clinicopathologic data were summarized. Development of local recurrence (LR) or distant metastasis (DM) was used to determine disease-free interval (DFI). Results: Among 112 patients during the study period, 35 met inclusion criteria. By histologic type, 23 patients had liposarcoma (66%), 9 leiomyosarcoma (26%) and 3 other (8.6%). Study patients were categorized by ethnicity: Caucasian (Group A, n = 12, 34%), Hispanic (B, n = 13, 37%), Asian/Middle Eastern (C, n = 10, 29%). A balanced distribution of histologic types was seen within each ethnic group. In Group A, neoadjuvant therapy (systemic or radiation) was given in only 1 patient in Group A (8.3%) versus 4 in B (30%) and 2 in C (20%) (Fisher’s exact test p = 0.44). No patient received adjuvant therapy in Groups A or B, while this was given in 2 additional patients in C (40% total). Disease progression (defined as either LR or DM) occurred in 4 out of 9 patients in A (44%), 2 out of 11 in B (18%) and 4 out of 8 in C (50%). Average DFI was 6 months in A, 5 in B and 8 in C. Conclusions: With the limitation as a single center study, our cohort was representative of the histologic types seen in RPS and all patients underwent a uniform approach to management. Potential differences in outcome after surgery were observed that may segregate by ethnic group. Although based on a small sample size, a trend of higher utilization of neoadjuvant therapy and a lower frequency of disease progression after surgery was noted in Hispanic versus non-Hispanic patients. The current study highlights the need for further investigation into the impact of ethnicity in RPS management.