(P 332) MARGINAL EXCISION OF EXTREMITY DEDIFFERENTIATED LIPOSARCOMA WITHOUT RADIATION MAY BE SAFE IN SELECT PATIENTS

Objective: Dedifferentiated liposarcoma (DDLPS) is a heterogeneous tumor comprising low-grade atypical lipomatous tumor (ALT) and high-grade sarcomatous components. This study evaluates local recurrence and metastasis rates in extremity DDLPS patients post-surgical resection, focusing on the impact of tumor grade at surgical margins and the role of adjuvant radiation therapy.

Methods: A retrospective analysis was conducted on 137 patients with pathologically confirmed extremity DDLPS who underwent surgical resection between 1995 and 2024. Outcomes assessed included local recurrence-free survival, metastasis-free survival, and overall survival. Statistical analyses utilized Chi-square tests for categorical variables, t-tests for continuous variables, and Kaplan–Meier methods for survival estimates.

Results: Among the 137 patients (mean age 67 years; mean tumor size 16 cm), 54.7% had negative surgical margins, while 45.3% had positive margins. Of those with positive margins, 48.3% involved only the ALT component. Notably, patients with positive margins confined to the ALT component who did not receive radiation therapy 40%(n=12) exhibited no local recurrences or metastases. From all of the patients in this study (n=137), those with negative margins treated without radiation therapy 28%(n=21), demonstrated low recurrence 4.7%(n=1) and metastasis 23%(n=5) rates.

Conclusion: In select extremity DDLPS cases where positive surgical margins are limited to the ALT component, marginal excision without adjuvant radiation therapy may be oncologically safe, offering comparable outcomes to those with negative margins. This approach can enhance functional preservation by avoiding unnecessary radiation exposure.

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