Clinicopathologic Prognostic Factors of Pure Myxoid Liposarcoma of the Extremities and Trunk Wall

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Abstract
Myxoid liposarcoma is generally considered a low grade tumor but the presence of areas of round cells exceeding 5% is reportedly associated with a worse prognosis. Whether “pure” tumors without round cells are low grade has not been confirmed. While radiotherapy has been used for patients’ myxoid liposarcoma it is unclear whether it reduces local recurrences. We therefore determined the survival, roles of radiotherapy for local control, and prognostic factors of pure myxoid liposarcoma of the extremities and trunk wall. We retrospectively reviewed 53 patients histologically diagnosed with pure myxoid liposarcoma arising in extremities and the trunk wall. Nine patients of the 53 received radiotherapy for primary tumors. Clinical features and prognosis was determined, and various factors were analyzed as to their usefulness as prognostic factors (age, gender, location, size, depth, surgical margin, and adjuvant radiotherapy). The minimum followup was 12 months (mean, 60 months; range, 12–226 months). Seven (13%) and 6 (11%) patients developed a local recurrence and distant metastasis, respectively. The 5- and 10-year disease-specific and disease-free survival rates were 90% and 83% and 77% and 77%, respectively. Radiotherapy had no impact on either overall or disease free survival. Age (older than 60 years) independently predicted worse overall and disease-free survival. In pure myxoid liposarcoma located in the extremities and trunk wall, relatively few patients developed distant metastasis suggesting the tumor is generally low grade. Local control could be achieved with wide surgical margins without radiotherapy. Age was associated with lower survival but size and depth were not. Myxoid liposarcoma in older patients requires special consideration for treatment and followup. Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.