Is the Thickness of the Margin Associated with Local Recurrence and Survival in Patients with Undifferentiated Pleomorphic Sarcoma?

<i>Background and Objectives</i>: Undifferentiated pleomorphic sarcoma (UPS) is a rare but aggressive soft tissue tumor. Achieving a tumor-free surgical margin is believed to be crucial for reducing local recurrence; however, the effect of margin thickness on recurrence and survival remains a matter of controversy. This study aimed to assess the association between histopathological margin status and outcomes, including local recurrence, disease-free survival (DFS), and overall survival (OS), in patients with UPS. <i>Materials and Methods</i>: We retrospectively analyzed 69 patients with histologically confirmed UPS, identified from a tertiary university hospital tumor database between January 2010 and December 2023. Patients were grouped by histopathological margin status as follows: >1 mm, ≤1 mm, or positive. Recurrence and survival outcomes were analyzed using Kaplan-Meier estimates, Cox regression, and multivariate logistic regression. Patients who underwent reoperation were also evaluated separately. <i>Results</i>: Minimum follow-up was 24 months (mean: 52.2 months). Local recurrence occurred in 21 patients, 20 of whom underwent reoperation. Positive margins were significantly associated with higher recurrence risk compared to the >1 mm group (OR: 17.6; 95% CI: 2.88-107.61; <i>p</i> = 0.0019). Although recurrence odds were lower in the ≤1 mm group than in the positive group, this was not statistically significant compared to the >1 mm group (OR: 0.52; 95% CI: 0.076-3.50; <i>p</i> = 0.498). In reoperated patients, surgical margin status was significantly associated with local recurrence (<i>p</i> = 0.0044), and overall survival tended to be longer in those with margins > 1 mm (67.3 ± 47.7 months) or ≤1 mm (50 ± 28.2 months) compared to positive margins (23.3 ± 17.3 months). A moderate negative correlation was observed between age and DFS (<i>p</i> < 0.001, r = -0.495). <i>Conclusions</i>: This study highlights the prognostic value of surgical margin status in patients undergoing reoperation for local recurrence. In this unique subgroup, margin status was significantly associated with recurrence risk, and patients with negative margins had improved overall survival compared to those with positive margins.