(P 342) PROGNOSTIC RELEVANCE OF TUMOR LOCATION IN MYXOID LIPOSARCOMA

Objective: Myxoid liposarcoma (MLS) is a common extremity soft tissue sarcoma with favorable local control, likely due to its radiosensitivity and expansile growth pattern. The influence of anatomic presentation on outcomes remains unclear.

Methods: We retrospectively reviewed 112 patients with localized MLS who underwent surgical resection. Tumors were classified by MRI into four anatomic types: superficial (n=14), intramuscular (n=23), intermuscular (n=33), and extracompartmental (n=23). Radiation therapy was given in 52 patients with large or high-grade tumors.

Results: Median follow-up was 63 months. Five- and ten-year local recurrence-free survival (LRFS) rates were 85% and 83%, respectively. Intramuscular MLS showed no local recurrence, with progressively higher recurrence in superficial (7.1%), intermuscular (9.1%), and extracompartmental (44%) types. Metastasis-free survival (MFS) was 83% at 5 years and 78% at 10 years, with the lowest metastasis rate in intramuscular tumors (4.4%). Disease-specific survival (DSS) was 94% and 89% at 5 and 10 years. Anatomic presentation, margin status, and radiotherapy influenced LRFS; tumor size and grade influenced MFS and DSS.

Conclusion: Anatomic presentation significantly impacts local control in MLS. Intramuscular MLS demonstrates excellent outcomes, suggesting that small, low-grade intramuscular tumors may not require radiotherapy. Anatomical classification may aid in individualizing treatment strategies.

Univariate Log-rank and multivariate Cox hazard analysis of prognostic factors.