Pathological prognostic factors of retroperitoneal liposarcoma: comprehensive clinicopathological analysis of 124 cases

Abstract

Background Retroperitoneal liposarcoma (RLS) is a type of rare malignant tumor. The aim of the present study was to study the correlations between the clinicopathological characteristics and the prognostic factors of RLSso as to delineate independent pathological indicators affecting prognosis. Methods The RLS pathological specimens were collected at Beijing Shijitan Hospital Affiliated to Capital Medical University from 2008 to 2018, and were used to study the histopathological features, including tumor size, histological types, lymphatic metastasis, tumor emboli in the blood and lymph vessels, and nerve invasion; immunohistochemical features, including Ki-67 and P53 proteins; and molecular pathological features, such as MDM2 (murine double minute2) gene amplification. Clinical treatment and follow-up data were collected, and the survival rate was calculated by Kaplan-Meier method. Univariate and multivariate survival analyses were performed to study the independent pathological factors. Results Of the 124 RLS cases, 63 were males (50.8%) and 61 were females (49.2%), with a median age of 52 years (range, 22-80 years). There were 51 cases (41.1%) of well-differentiated liposarcoma, 73 cases (57.3%) of dedifferentiated liposarcoma (DDL); 3 cases (2.4%) with lymph node metastases; 4 cases (3.2%) with tumor emboli in the vessels; 21 cases (16.9%) with Ki-67 label index <20% and 103 cases (83.1%) with Ki-67 label index ≥20%; and 81 cases (65.3%) with P53 <60% and 43 cases (24.7%) with P53 ≥60%. Fluorescence in situ hybridization studies revealed MDM2 gene amplification. Univariate analysis found the following pathological factors were correlated with prognosis: histopathological classification, recurrence, mitosis, tumor necrosis, Ki-67 label index, and P53. Multivariate analysis by Cox proportional hazard model found the following three independent pathological prognostic factors: age [hazard ratio (HR): 1.798, P=0.018], tumor site (HR: 1.263, P=0.002), tumor necrosis (HR: 1.984, P=0.024), and recurrence (HR: 2.161, P=0.049). Conclusions Age, tumor necrosis, tumor site, and recurrence could be independent pathological prognostic factors for RLS.