Search

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.

Objective: To evaluate the impact of malignancy grade and the proportion of the dedifferentiated component (DC) in retroperitoneal dedifferentiated liposarcomas (DDLS) on the course and prognosis of the disease., Material and Methods: The retrospective study enrolled 74 patients with primary retroperitoneal DDLS who underwent radical surgical treatment in the N.N. Blokhin National Medical Research Center of Oncology, Ministry of Health of Russia. Histological surgery specimens from all cases of DDLS were reexamined and reclassified. According to malignancy grades and the proportion of the dedifferentiated component in the tumor, the patients were divided into the comparison groups included in the intergroup analysis of overall and relapse-free survival (OS and RFS) rates. The authors also analyzed the relationship between the proportion of the dedifferentiated component in DDLS and the frequency of adjacent organ invasion., Results: Patients with a more than 15% dedifferentiated component had significantly lower OS rates than those with a less than 15% one ( p =0.0001; log-rank test). The median OS in the DDLS group with a less than 15% dedifferentiated component was 91 months (95% CI, 82-100); that in the DDLS group with a more than 15% dedifferentiated component was 29 months (95% CI 17-41). The 5-year overall survival rates in the groups with less than 15% and more than 15% dedifferentiated components were 69% and 2%, respectively. The group with a more than 15% dedifferentiated component had significantly lower RFS rates than that with a less than 15% one ( p =0.0001; log-rank test). In the DDLS groups with less than 15% and more than 15% dedifferentiated components, the median RFS rates were 25 months (95% CI 23-27) and 13 months (95% CI 8-18), respectively. In these groups, the 2-year RFS rates were equal to 50% and 9%, respectively. In the DDLS groups with less than 15% and more than 15% dedifferentiated components, pathologically confirmed invasion into the adjacent organs was observed in 32% and 63% of cases, respectively. There were no statistically significant differences in the OS and RFS of patients with DDLS according to tumor grade ( p =0.069; p =0.102)., Conclusion: This investigation suggests that DDLS have a more aggressive course with an increasing proportion of the dedifferentiated component in the tumor. Considering the histological variability in the dedifferentiated component, which is demonstrated in the research and scientific literature, as well as lack of a prognostic impact of histological grade, the authors believe that semi-quantitative assessment of the proportion of the dedifferentiated component in DDLS is able to serve as a simple and efficient morphological marker for the course of the disease and prognosis in retroperitoneal DDLS.