(P 397) EXPLORING REAL WORLD DATA OF RECURRENCE IN NON-METASTATIC MYXOFIBROSAROMA: AN UPDATED RETROSPECTIVE COHORT STUDY

Objective: Myxofibrosarcoma is a rare subtype of soft tissue sarcoma characterized by its locally infiltrative behavior and high recurrence rates. It accounts for approximately 5% of all soft tissue sarcomas and typically affects older adults in their sixth or seventh decade. Local recurrence rates are as high as 50-60% especially in cases where positive margins are present. Many prior studies have reported an association between recurrence and prior radiation for other cancers, however there is a paucity of literature investigating the real world outcomes of recurrence.

Methods: Building upon a prior review, we conducted an IRB-approved retrospective cohort study of patients diagnosed with non-metastatic primary myxofibrosarcoma at the University of Miami from 2008 to 2024. Data on demographics, clinical characteristics, treatments, and outcomes were extracted from electronic medical records with attention to recurrence, local versus distant recurrence, and if local recurrence was within the prior radiation field. Detailed treatment timelines were collected including the original control method and the sequence of treatments. Kaplan-Meier curves and logistical regression models were used for survival analysis using the R statistical programming language.

Results: 99 patients with non-metastatic myxofibrosarcoma were identified with recurrence observed in 36 patients (36.4%), Of the patients who recurred, 10 patients had distant recurrence (45.5%), 5 had local recurrence without prior radiation (22.7%), and 7 had local recurrence within a prior radiation field 7 (31.8%). Patients treated with radiation first had significant increased odds of distant recurrence OR 11.85 (p < 0.001). Patients who received systemic therapy first had decreased odds of any recurrence, OR 0.38 (p 0.03). Patients who received surgery first had increased odds of local recurrence, OR 3.03 (p 0.02).

Conclusion: The findings suggest that having surgery first is a significant predictor of local recurrence in non-metastatic myxofibrosarcoma. Radiation therapy seems to prevent local recurrence at the site but in those patients there is an increased rate of distant recurrence. We are collaborating with additional sarcoma centers in Florida to expand our cohort for additional analysis. We hope to use this data to improve outcomes and prevent recurrence... We plan to use this preliminary data to further the study on effective management of sarcoma in a multidisciplinary context to improve patient outcomes.