9:00-9:10 am Metastatic Epidural Cervical Spinal Cord Compression CSRS San Diego, 2015 Michael G. Fehlings, MD

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1 9:00-9:10 am Metastatic Epidural Cervical Spinal Cord Compression CSRS San Diego, 2015 Michael G. Fehlings, MD 1 BACKGROUND After the lungs and the liver, metastases most frequently arise in osseous tissues; the spinal column is the commonest bony location. 1,2 Peak incidence of spinal metastases is in patients 40 to 65 years of age and they most often result from prostate, breast, kidney, lung, and thyroid primary cancers Not all bone metastases are clinically significant; 30-90% of patients who die from cancer are found to have bone metastasis at autopsy 2,4. Symptomatic Metastatic Epidural Spinal Cord Compression (MESCC) is described as an extradural mass (1) indenting the dural sac of the spinal cord or cauda equina and (2) causing one or more clinical features, such as focal axial or radicular pain, motor weakness, sensory disturbance, sphincter or sexual dysfunction, and gait abnormality 4,5. A population-based study reported that among American patients dying of cancer, the annual incidence of MESCC hospitalization was 3.4%. 6 Given that approximately 589,400 Americans will die of cancer in 2015, over 20,000 of these patients would have likely been hospitalized as a result of MESCC prior to their death. Since the 5-year relative survival rate for all cancers keeps improving 7, the incidence of symptomatic spinal metastatic disease will likely continue to increase. IMPACT OF SURGERY MESCC is amongst the most dreaded complications of cancer. Its natural history involves progressive debilitating pain and irreversible neurological deficits. Overall, MESCC is associated with shortened survival and worsened quality of life. 1,4,8-10 In the context of systematic metastatic disease, treatment goals are to optimize quality of life via palliative care to address symptoms such as pain, to preserve or improve neurological functions, and to achieve spinal mechanical stabilization. 4,10,11 Since it is now largely recognized that modern spinal surgery combined with radiation therapy (RT) provides better clinical outcomes than RT alone 12-14, and is cost-effective 15, surgery is usually the favored initial treatment for selected patients with single level MESCC. 12,16-20 Fehlings et al. (Unpublished data: article accepted for publication in the Journal of Clinical Oncology) evaluated a cohort of 142 surgically treated patients, with a single symptomatic MESCC lesion compressing the spinal cord, enrolled in a prospective multi-center study conducted by AOSpine North America. The median survival was 7.7 months; mortality rates were 9% and 62% at 30-day and 12-month, respectively. There was post-operative improvement (a) at 6 months for ambulatory status (McNemar s test, p < ), lower extremity and total motor scores (Wilcoxon Signed Rank Test, p < and , respectively), and (b) at 6 weeks, 3, 6, and 12 months for Oswestry Disability Index (ODI), EuroQol 5 dimensions (EQ-5D), and pain interference (paired t test, p < ). Moreover, at 3 months after surgery the American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade was improved (Stuart-Maxwell test p = ). SF-36 scores improved postoperatively in 6 out of 8 domains. The incidence of wound complications was 10% and 2 patients required a second surgery (screw malposition and epidural hematoma). Therefore, surgery, as an adjunct to radiation and chemotherapy, provides immediate and sustained improvement in pain, neurological, functional, and HRQoL outcomes with acceptable risks in patients with a focal symptomatic MESCC lesion who are given at least 3 month life expectancy.

2 2 CERVICAL SPINE Although the cervical spine is the least involved in MESCC, up to 15% 1,3,4, if left untreated these may result in a higher likelihood of neurological deficits. 21 An et al. 22 and Le et al. 23 reported a 100% rate of myelopathy, which may be explained by the relative narrowness of the cervical spinal canal, as well as the fact that the cervical spine is prone to kyphosis, and the susceptibility of the lower cervical spinal cord to ischemic injury given the specificity of its vascular supply. 21 In the context of metastatic spinal disease, the latter particularities of the cervical spine may influence spinal surgeons to attempt decompression and stabilization procedures to preserve or enhance quality of life. The evidence related to the surgical treatment of cervical metastases is limited to retrospective case series (Level III). In their systematic literature review, Fehlings et al. 21 report that the cervical anatomic region, namely the occipitocervical (C0-C1), subaxial (C2- C6) and cervicothoracic (C7-T1), influences not only treatment decisions, but also the type of surgical intervention. Based on the results of their systematic review and a modified Delphi consensus approach of the Spine Oncology Study Group (SOSG), the authors concluded and recommended: In addtion, in their literature review on the management of craniovertebral junction metastases, Moulding et al. 24 specified that, in patients with normal spinal alignment or minimal fracture subluxations, conventional external beam radiation therapy or stereotactic radiosurgery was the mainstay treatment of patients. However, patients with either fracture subluxations greater than 5mm or 3.5 mm subluxation with 11-degree angulation should be

3 3 considered for surgery. Given the morbidity associated with anterior approaches and the goal of surgery being palliative in nature, the authors advocated posterior approaches involving only decompressing laminectomy. Occipito-cervical and posterior C1-C2 or C1-C3 instrumentation with screws and rods was effective in patients with irreducible subluxations and reducible subluxations, respectively. Moreover, Kato et al. 25 highlighted that in any MESCC patients deemed to be appropriate surgical candidates, internal fixation for mechanical instability using sublaminar Luque instrumentation was valuable to improve pain. Their criteria for instability were: (1) subluxation of >5mm, (2) 70% unilateral condylar destruction, or (3) >50% bilateral destruction. SINS A milestone study conducted by Fisher et al. 26 proposes the Spinal Instability Neoplastic Score (SINS), a scoring system to accurately and reliably predict spinal instability in patients with spinal tumours. The SINS considers six aspects involved in assessing spinal stability. SINS allows the classification of patients as either stable, potentially unstable, or unstable. Consequently, SINS helps clinicians, including family, emergency doctors, oncologists, and spinal surgeons, identifying patients at risk of spinal instability, thus assisting treatment decision making. In addition, SINS eases communication not only between specialists during the referral process, but also with patients. SINS is the first classification system for tumorrelated instability shown to be reliable and valid. Stable: 0-6 points Potentially unstable: 7-10 points Unstable: points

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