Surgeon’s perception of margins in spinal en bloc resection surgeries: how reliable is it?

Purpose and Background: En bloc resections aim at surgically removing a tumor in a single, intact piece, fully encased by a continuous shell of healthy tissue—the “margin”. Intraoperative continuous assessment of the plane of resection regarding the tumor’s margins is paramount. The goal of this study was to evaluate the accuracy of experienced spinal tumor surgeons’ perception of these margins. Methods: A retrospective analysis of a prospectively collected data of 1681 patients affected by spine tumors of whom 217 en bloc resections was performed. Surgeons’ intraoperative assessment was compared to the histopathological assessment. Results: Most were primary—163 (42 benign and 121 malignant), metastases occurred in 54 cases. ‘Wide’ margins were obtained in 126 cases; ‘marginal’ in 60 cases, and ‘intralesional’ in 31 cases. Surgeons assessed clear margins in 109 cases and contaminated in 108 cases. When considering marginal margins as a contaminated resection, the surgeon’s assessment of clear resection had a sensitivity of 76.89%, specificity of 86.81%, PPV and NPV (positive and negative predictive values) were 88.99 and 73.15%, respectively. Inter-observer agreement was 0.62. When considering marginal margins as a clear resection, the surgeon’s assessment of clear resection had a sensitivity of 64.5%, specificity of 100%, PPV and NPV were 100 and 0%, respectively. Inter-observer agreement was 0.29. Conclusion: Surgeons are fairly accurate in their intraoperative assessment of clear margins achieved; however, this accuracy is not perfect and exploring ways to improve this intraoperative assessment is of major importance possibly impacting the outcome of the treatment.