Feasibility and oncologic outcome of En bloc resection with intentional tumor transgression in primary spinal sarcoma: The Korean Society of Spinal Tumors multicenter study (KSST 2024–02)

Introduction: Primary spinal sarcoma is rare and technically challenging, particularly when attempting en bloc resection with negative margins. Intentional tumor transgression may be used when Enneking-appropriate en bloc resection is not feasible, but its oncologic implications remain unclear. This study evaluated the feasibility and outcomes of en bloc resection with intentional tumor transgression compared with other resection strategies. Methods: This multicenter retrospective study included patients who underwent surgery for primary spinal sarcoma across five tertiary hospitals from 2000 to 2022. Patients were grouped by resection method: (A) en bloc resection with negative margins, (B) en bloc resection with intentional tumor transgression, (C) piecemeal resection, and (D) subtotal resection. Tumor extent was assessed using a modified Weinstein-Boriani-Biagini classification. The primary outcome was overall survival; secondary outcomes included local recurrence, distant metastasis, and perioperative complications. Results: The study included 119 patients (mean age 46.0 ± 19.8 years). Oncological outcomes (overall survival, local recurrence, and distant metastasis) demonstrated significant trends in survival analysis across groups A to D. Although Group B had more extensive disease (>3 quadrants, canal encroachment, multi-level involvement), its overall survival, local recurrence, and distant metastasis did not differ significantly from Group A (hazard ratio [HR] 0.54, p = 0.467; HR 0.46, p = 0.307; HR 0.46, p = 0.237, respectively). Complication rates were comparable between groups A and B. Conclusion: En bloc resection with intentional tumor transgression offers oncologic outcomes comparable to margin-negative en bloc resection in selected patients with more extensive tumors. This technique may be a viable alternative when Enneking-appropriate en bloc resection is not feasible.