(P 457) A RETROSPECTIVE REVIEW OF LOW-GRADE FIBROMYXOID SARCOMA: SURGICAL MANAGEMENT, RADIATION THERAPY, AND OUTCOMES

Objective: Low-grade fibromyxoid sarcoma (LGFMS) is an ultra-rare soft tissue sarcoma with deceptively benign histologic features yet a potential for late recurrence and metastasis, necessitating lifelong surveillance despite its generally favorable prognosis. This study retrospectively evaluates the oncologic outcomes of LGFMS, examining how tumor location, surgical margin status, and use of neoadjuvant and adjuvant radiation therapy impact recurrence and survival.

Methods: We conducted a single institution retrospective analysis of 19 patients treated between 1998 and 2024 with histologically confirmed LGFMS and who met inclusion criteria for complete surgical, adjuvant, and follow-up data.

Results: Within the patient cohort, the median age at presentation was 40.0 years (IQR 24.0-56.8), and 58% were female. Tumors most commonly arose in the lower extremity (42%), followed by the upper extremity (21%) and trunk (21%). The majority were in deep (intramuscular) compartments (53%) with a median tumor size of 6.8 cm (IQR 4.5-8.7). Negative margins (R0) were achieved in 58% of cases, while 32% had microscopic residual margins (R1), and 11% had gross residual margins (R2). All patients underwent primary resection; two patients (11%) received pre-operative radiation, and three patients (16%) received post-operative radiation. Among patients who received radiation therapy, metastasis occurred in one patient with negative margins following pre-operative radiation. At a median and average follow-up of 4 and 6.5 years, respectively, 2 patients had recurrence after non-oncological resection. There were no recurrences after oncological resection.

Conclusion: In this retrospective review of 19 patients with LGFMS, recurrence was observed in over 10% (2/19) of cases despite surgical resection, while distant metastasis was rare (1/19). Additional studies are needed to confirm the role of radiation therapy in preventing disease progression. The recurrence patterns observed represent an important area for further exploration to better inform surgical decision-making and optimize long-term outcomes.

Clinical characteristics of the 19 patients with LGFMS