(P 374) FACTORS ASSOCIATED WITH RECURRENCE IN DEDIFFERENTIATED RETROPERITONEAL LIPOSARCOMA: ANALYSIS AT A REFERENCE CENTER

Objective: This study aimed to identify prognostic factors associated with recurrence in dedifferentiated retroperitoneal liposarcoma (DDLPS).

Methods: We conducted a retrospective analysis of medical records of DDLPS patients, examining clinical and pathological variables associated with disease recurrence, including age, gender, tumor size, degree of differentiation, location, vascular invasion, and treatment.

Results: We analyzed 55 cases of DDLPS. Among these, 32 (58.2%) were male, with a mean age of 54.30 years (±13.34) and a mean tumor size of 29.28 cm (±11.64). The most common symptom was an abdominal tumor. Forty-two patients were treated for the first time, and 13 had recurrences after treatment at low-volume centers. The median surgical time was 3.25 hours (range 1-9). Multivisceral resection was performed in 51.4% of cases, with the kidney (61.8%) being the most frequently resected organ, followed by the colon (30.9%). Vascular involvement was present in six cases (10.9%), with the inferior vena cava being the most frequently affected vessel. Postoperative morbidity occurred in 12% of cases (6 patients), and mortality was 5.3% (2 cases). During follow-up, recurrences occurred in 30 patients (54.5%): 22 patients had one recurrence, 4 had two, and 3 had more than three recurrences. Distant recurrence was observed in 5 patients (9.1%). Multifocal primary tumors were found in 12 patients (31.6%), and sarcomatosis at initial diagnosis or recurrence was observed in 3 patients (7.9%). Overall survival (OS) was 39.76 months (range 16-50), and the disease-free interval was 19.9 months (range 13-28). Factors associated with recurrence included the involvement of adjacent organs (p=0.01), vascular invasion (p< 0.05), and treatment at a low-volume center (p=0.03).

Conclusion: Our study underscores the significance of vascular invasion and treatment at a low-volume center as key prognostic factors in the recurrence of dedifferentiated retroperitoneal liposarcoma. These findings help identify patients at higher risk of recurrence and inform clinical decision-making to improve outcomes in managing this disease.