11546 Background: Surveillance imaging of patients with retroperitoneal liposarcoma (RP-LPS) following surgical resection is based on a projected risk of locoregional and distant recurrence. The duration of surveillance is not well defined as the long-term natural history of RP-LPS after treatment is poorly understood. We evaluate a cohort of RP-LPS patients—without evidence of disease 10 years following initial resection—to assess the long-term risk of recurrence and disease-specific survival (DSS). Methods: The prospectively maintained UCLA Sarcoma Database was used to identify RP-LPS patients who demonstrated 10-year progression-free survival (10yr-PFS) after initial diagnosis and treatment. Patients in the 10yr-PFS cohort were subsequently evaluated for recurrence and DSS. Time intervals start at date of initial surgical resection. Cox proportional hazards models were used to determine factors associated with recurrence and DSS. Results: From 1972-2010, 76 patients with RP-LPS had at least 10 years of follow-up. Of these, 37 (49%) demonstrated 10yr-PFS. Median follow-up was 15 years (range 10-35 years). Among the 10yr-PFS patients, 43% (16/37) developed a recurrence >10 years after the initial surgery, and 19% (7/37) died of disease. Neither long-term recurrence nor DSS were significantly associated with age, sex, tumor size, LPS subtype, surgical margin, or peri-operative treatment with radiation or chemotherapy (Table). Conclusions: Patients with primary RP-LPS treated with surgical resection +/- multimodality therapy have a long-term risk of recurrence and disease-specific death that is unacknowledged by current surveillance imaging guidelines. Among the patients with a 10yr-PFS, 43% developed a recurrence and 19% died of disease. These findings suggest a need for lifelong surveillance imaging in patients with RP-LPS.[Table: see text]
Massive retroperitoneal liposarcoma
