Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Canada.
J Neurosurg Spine. 2013 May;18(5):430-5. doi: 10.3171/2013.2.SPINE12739. Epub 2013 Mar 15.
Spine stereotactic radiosurgery (SRS) is increasingly being used to treat metastatic spinal tumors. As the experience matures, high rates of vertebral compression fracture (VCF) are being observed. What is unknown is the mechanism of action; it has been postulated but not confirmed that radiation itself is a contributing factor. This case report describes 2 patients who were treated with spine SRS who subsequently developed signal changes on MRI consistent with tumor progression and VCF; however, biopsy confirmed a diagnosis of radiation-induced necrosis in 1 patient and fibrosis in the other. Radionecrosis is a rare and serious side effect of high-dose radiation therapy and represents a diagnostic challenge, as the authors have learned from years of experience with brain SRS. These cases highlight the issues in the new era of spine SRS with respect to relying on imaging alone as a means of determining true tumor progression. In those scenarios in which it is unclear based on imaging if true tumor progression has occurred, the authors recommend biopsy to rule out radiation-induced effects within the bone prior to initiating salvage therapies.
脊柱立体定向放射外科（SRS）越来越多地用于治疗转移性脊柱肿瘤。随着经验的成熟，观察到椎体压缩性骨折（VCF）的发生率很高。目前尚不清楚其作用机制；有人推测但尚未证实放射本身是一个促成因素。本病例报告描述了 2 例接受脊柱 SRS 治疗的患者，随后 MRI 上出现与肿瘤进展和 VCF 一致的信号改变；然而，活检在 1 例患者中证实为放射性坏死，在另 1 例患者中证实为纤维化。放射性坏死是大剂量放疗的一种罕见且严重的副作用，代表了诊断上的挑战，作者从多年的脑部 SRS 经验中了解到这一点。这些病例凸显了脊柱 SRS 新时代在仅依靠影像学作为确定真正肿瘤进展手段方面的问题。在根据影像学尚不清楚是否发生真正肿瘤进展的情况下，作者建议在开始挽救治疗之前进行活检，以排除骨内的放射效应。
