Prognostic groups in retroperitoneal well-differentiated and dedifferentiated liposarcomas

Abstract

Introduction. Liposarcoma is the most common retroperitoneal sarcoma. The majority of retroperitoneal liposarcomas are represented by highly differentiated and dedifferentiated liposarcomas. To date, clinical practice has not developed an effective method of the stratification of patients with RLPS into prognostic groups to determine the tactics of patient management. Objective. To develop a method for stratification of patients with retroperitoneal well-differentiated (WDLPS) and dedifferentiated (DDLPS) liposarcomas into prognostic groups. Materials and methods. A retrospective study included 111 patients with WDLPS and 74 patients with DDLPS. The staging of the disease was carried out according to the modified TNM-classification, the analysis of survival was performed depending on the histological type of retroperitoneal liposarcoma (RLPS), the effect of age on overall survival (OS) was evaluated in WDLPS and DDLPS. Further, multivariate Cox regression analyzes were performed to assess the independent factors influencing the prognosis of patients. Then, we developed a methodology for stratification of patients into prognostic groups. OS and recurrence-free survival (RFS) were analyzed in accordance with it.Results and discussion. OS and RFS were statistically significantly worse in DDLPD compared with WDLPS (p = 0.000; log-rank test). At the same time, the results of the work demonstrated the absence of a statistically significant difference in OS and RFS depending on the degree of malignancy of DDLPS. In case of WDLPS and DDLPS, significant differences in OS were achieved only between groups of patients whose age was (at the time of the initial detection of RLPS) under 60 years and older (p = 0.008; p = 0.026; logrank test). Thus, the borderline value of the age of patients, which affects the prognosis, was determined – 60 years. OS and RFS were statistically significantly different between all prognostic groups (p = 0.000; log-rank test). The highest OS was achieved in the group with a “favorable prognosis”, while the shortest OS was in the group with the extremely poor prognosis (p = 0.000; log-rank test). The median OS in the “favorable prognosis” group was 225 (95% CI, 174, 276) months; in the “intermediate prognosis” group – 130 (95% CI, 115, 145) months; in the “poor prognosis” group – 90 (95% CI, 79, 101) months; in the “extremely poor prognosis” group – 22 (95% CI, 15, 29) months. The highest RFS was achieved in the group with a “favorable prognosis”, while the shortest RFS was achieved in the group with an “extremely poor prognosis” (p = 0.000; log-rank test). The median RFS in the “favorable prognosis” group was 80 (95% CI, 65, 95) months; in the “intermediate prognosis” group – 47 (95% CI, 33, 61) months; in the “poor prognosis” group – 26 (95% CI, 24, 28) months; in the “extremely poor prognosis” group – 10 (95% CI, 6, 14) months.Conclusion. The proposed method for stratification of patients with RLPS into prognostic groups demonstrates an adequate distribution of patients and the reliability of intergroup differences in the survival rate.

Keywords

• retroperitoneal liposarcoma
• liposarcoma
• prognosis
• retroperitoneal tumors
• prognostic groups
• well-differentiated liposarcoma
• dedifferentiated liposarcoma