Classification and Prognostic Role of Histological Organ Infiltration after Multivisceral Surgery in Primary Retroperitoneal Liposarcomas

Background Retroperitoneal liposarcomas represent a group of rare malignant neoplasms of adipocytic origin characterized by complex clinical management and often a poor prognosis. For their strong tendency to local recurrence, in the last 20 years, aggressive surgery has established itself as a cornerstone of the treatment. Despite the advancement in neoadjuvant treatment and the implementation of the surgical technique, the risk of local recurrence and systemic progression remains high and determines the prognosis of patients. Efforts have been made, and several significant prognostic factors have been described and are now currently applied in clinical practice. Histological involvement of the organs excised during surgery for retroperitoneal liposarcoma is a frequent finding. The extent of histological organ involvement (HOI) to organs and structures may have prognostic implications. This study investigated the prognostic role of HOI in these patients. Method Patients undergoing multivisceral surgery for primary retroperitoneal liposarcomas in two referral centers were identified retrospectively. Clinical and histopathological data were collected from a prospectively maintained database, revised and analyzed. HOI was the variable of interest and was classified into four degrees: absent (HOI-0), perivisceral (HOI-1), initial (HOI-2), and advanced (HOI-3). The primary endpoint was the prognostic correlation of HOI degree with overall survival (OS). The second endpoint was the prognostic correlation of HOI degree with disease-free survival (DFS). The prognostic value of HOI was adjusted for preoperative treatment and the Sarculator® nomogram score. Results 109 patients were included. HOI-0, HOI-1, HOI-2, and HOI-3 were detected in 9 (8.3%), 11 (10.1%), 43 (39.4%), and 46 (42.2%). Median follow-up was 8.4 years (IQ-range 7.2-9.6 years). 68 recurrences and 50 patient deaths were observed, resulting in a 10-year OS and DFS of 51.1% [95% Confidence Interval (CI) 41.9-62.1%] and 34.1% (95%CI 25.2-46.1%), respectively. Clinically relevant HOIs (HOI-2 and HOI-3) were found in 35/45 (77.8%) and 54/64 (84.4%) cases of well- and de-differentiated liposarcomas, respectively. On multivariable survival analysis, patients with HOI-3 had significantly shorter OS (HOI-3 vs. HOI-0/HOI-1 HR=2.92; p=0.012) and DFS (HOI-3 vs. HOI-0/HOI-1 HR=2.23; p=0.045), independently of the nomogram score (OS: HR=2.93; p<0.001; DFS: HR=1.78; p=0.003). Conclusion Advanced HOI is frequently detected in primary retroperitoneal liposarcoma patients and is associated with a worse prognosis.