Surgical Margin Analysis in Osteosarcoma: Impact on Survival and Local Control.

Background/objectives: The quality of surgical margins has been shown to be a prognostic factor in many sarcoma entities, yet its role in osteosarcoma remains controversial. While previous studies have shown that the outcome was not related to the margin width in bone, the impact of the extraosseous margin width (margin at the soft tissue invasion)-which needs to be close sometimes due to neurovascular structures-needs to be assessed. This study aims to evaluate the influence of soft tissue surgical margins on local recurrence and overall survival in patients with high-grade osteosarcoma.

Methods: We conducted a retrospective, single-center study including 75 patients treated for high-grade osteosarcoma. All patients underwent standardized neoadjuvant chemotherapy followed by complete surgical resection. Patients were stratified into three groups based on the histological margin width of the extraosseous parts: group 1 (<1 mm), group 2 (1-5 mm), and group 3 (≥5 mm). Primary endpoints were local recurrence and overall survival (OS), analyzed using Kaplan-Meier estimates, log-rank tests, and Cox regression.

Results: Local recurrence occurred in seven patients (9%). Although the overall comparison between the three groups was not statistically significant ( = 0.074), a subgroup analysis revealed a significantly higher recurrence rate in patients with margins < 1 mm compared to those with wider margins ( = 0.024). No significant differences in overall survival (OS) were observed between the groups ( = 0.896). Tumor location, metastatic status, and UICC stage were significant predictors for both endpoints in univariate analysis. However, none of these association were confirmed in multivariate analyses.

Conclusions: Very close surgical margins (<1 mm) may increase the risk of local recurrence in high-grade osteosarcoma; however, they do not appear to affect overall survival.