The Role of "Tumor-Free Margins" in the Resection of Spinal Tumors: Who Should Be Treating Spine Tumors?

En bloc resection is a surgical procedure attempting to remove the whole tumor in a single piece, intact, encased by a continuous cuff of healthy (tumor-free) tissue. This cuff is called the "margin": its quality and thickness defines the oncologic feature of the procedure. When en bloc resection is planned in the treatment of bone tumors of the spine, obtaining a tumor-free margin can be extremely difficult and is a much more frequent problem in the axial spine than in limb tumors. Structures, such as the spinal cord and the vital vascular anatomy in and around the spine, present challenges that make achieving tumor-free margins impossible or difficult at best. The authors' experience is based on the treatment of 1072 bone tumors of the spine (515 primary tumors)-145 of them treated by en bloc resection-and on the literature review, which stresses the close relationship between the adequacy of the margins and the local control in aggressive benign and in low-grade malignant tumors. The authors have worked with the international community of spine oncologic surgeons to provide an accepted approach for these most difficult cases and in this article discuss in detail the results from 2 Italian institutions with the largest experience presented to date. Recently, one of the authors (JW), while in China at a spine tumor conference, heard over 900 cases of spine tumors presented from various institutions all across China. In each case the authors presented their cases using the Weinstein Boriani Biagini (WBB) classification system for defining treatment and their results were similar to what is being presented here. It is also clear that with high-grade malignant tumors the important role of specific chemotherapy protocols and various types of radiation therapy (eg, traditional vs. proton beam vs. others) must be considered as well. Effective surgical intervention must be measured against the consequences associated with approaching some of these cases. For some patients, surgical intervention can be worse than no intervention, and the possible consequences of each case must be weighed by patient and physician against the patient's preferences and values; informed patient choice is very important here. At present, lacking randomized trial-based conclusions, we recommend en bloc resection with appropriate margins in low-grade malignant tumors, when feasible. The rate of local recurrence is often directly related to surgical margins obtained when comparing marginal/wide to intralesional resections. When the criteria for performing these difficult procedures are not met and/or when patients choose to save relevant functional abilities (eg, bowel/bladder, incomplete or complete paralysis) over resections that are oncologically preferred, adjuvant treatments must be used knowing higher rates of local recurrence and other associated complications should be expected.