Long-term survival with eribulin in an elderly patient with inoperable retroperitoneal well-differentiated liposarcoma: a case report and literature review.

Background: The management of retroperitoneal well-differentiated liposarcoma (WDLPS) in elderly, surgically ineligible patients remains a therapeutic challenge. Eribulin, a microtubule inhibitor, has demonstrated activity in advanced non-WDLPS liposarcoma subtypes; however, its efficacy in pure well-differentiated liposarcoma (WDLPS) remains exploratory, and long-term outcomes in elderly patients are not well documented. Case presentation: An 82-year-old female presented with a large retroperitoneal mass. Biopsy confirmed WDLPS with MDM2 amplification. Due to age, comorbidities, and unresectable disease, first-line therapy with anlotinib was initiated. However, treatment was complicated by a hypertensive crisis and radiological evidence of slow disease progression. Therapy was switched to second-line eribulin (1.4 mg/m² on days 1 and 8 of a 21-day cycle). Results: The patient has maintained sustained disease stability for over five years while receiving continuous eribulin treatment, as confirmed by serial CT imaging assessed using RECIST criteria version 1.1. Treatment has been well tolerated, with adverse events limited to Grade I-II leukopenia and no significant neurotoxicity or gastrointestinal effects. The patient's quality of life and glucose homeostasis (Doege-Potter syndrome-associated hypoglycemia) have been well preserved throughout this period. Conclusion: This case suggests that eribulin may provide durable disease control and is a well-tolerated therapeutic option for elderly patients with inoperable retroperitoneal WDLPS, providing preliminary evidence for its potential to achieve long-term tumor stability and maintain quality of life in this vulnerable population. Multidisciplinary assessment and individualized treatment strategies remain essential in optimizing outcomes.