Metastatic Spinal Tumors

Neurosurg Focus 11 (6):Article 1, 2001, Click here to return to Table of Contents Metastatic spinal tumors ROBERT F. HEARY, M.D., AND CHRISTOPHER M. BONO, M.D. The Spine Center of New Jersey, New Jersey Medical School, Newark, New Jersey; and Department of Orthopaedic Surgery, Division of Spine Surgery, University of California at San Diego Medical Center, San Diego, California Metastatic spinal tumors are the most common type of malignant lesions of the spine. Prompt diagnosis and iden- tification of the primary malignancy is crucial to overall treatment. Numerous factors affect outcome including the nature of the primary cancer, the number of lesions, the presence of distant nonskeletal metastases, and the presence and/or severity of spinal cord compression. Initial management consists of chemotherapy, external beam radiotherapy, and external orthoses. Surgical intervention must be carefully considered in each case. Patients expected to live longer than 12 weeks should be considered as candidates for surgery. Indications for surgery include intractable pain, spinal cord compression, and the need for stabilization of impending pathological fractures. Whereas various surgical approaches have been advocated, anterior-approach surgery is the most accepted procedure for spinal cord decom- pression. Posterior approaches have also been used with success, but they require longer-length fusion. To obtain a sta- ble fixation, the placement of instrumentation, in conjunction with judicious use of polymethylmethacrylate augmentation, is crucial. Preoperative embolization should be considered in patients with extremely vascular tumors such as renal cell carcinoma. Vertebroplasty, a newly described procedure in which the metastatic spinal lesions are treated via a percutaneous approach, may be indicated in selected cases of intractable pain caused by non- or minimally fractured vertebrae. KEY WORDS • metastasis • spine • tumor • tumor excision Bone is the third most frequent metastatic site of distant tion is not always clear cut. Although various attempts spread of carcinoma.4 The vertebral column is the most have been made to devise methods for predicting life ex- common site of skeletal metastases.13 Improvements in pectancy in this population, none exists.10,31,33,37,39 Regard- oncological management have increased survival times in less, most authors agree that patients in whom expected patients with skeletal metastases. Spine surgeons are fre- survival is at least 12 weeks should be considered for pal- quently faced with decisions of how to treat patients with liative surgery. Numerous other factors must be weighed, these lesions. Although not curative, resection and stabi- however, including overall health, nutrition, the aggres- lization can have beneficial effects on neurological status, siveness of the primary tumor, and extent of preoperative function, pain, and mobility.14,17,18,24,25 These are important neurological deficit(s).31,33,37 issues, particularly in individuals in whom remaining life Once the decision for surgery has been made, the goals expectancy is no more than 1 to 2 years.38 can be more defined. If the neural elements are com- Metastatic disease of the spine can manifest in many pressed, the first fundamental step is to undertake decom- ways. Pain is present in virtually all cases and can be se- pressive surgery, excising either the anterior or posterior vere enough that basic activities such as walking become elements. Resection of tumoral material is also effective nearly impossible.9 Significant bone destruction can lead for pain relief. With various methods available, recon- to fracture, instability, and deformity. Perhaps the most struction of the spine, in which cement augmentation, dreaded complication, spinal cord compression, can result bone graft, and instrumentation can be used, is crucial for 5,17,24,25,36 from pathological fractures, direct invasion of the spinal achieving fixation. There are strong supporters of 16,20,29,35 posterior surgery over anterior surgery, whereas others canal by the tumor, or osteoblastic bone reaction. 5,9,30 Surgical treatment has a role in each of these scenarios; favor combined approaches. New minimally invasive however, the decision to proceed with operative interven- techniques, such as vertebroplasty, may also play a role for the prophylactic spinal fixation before significant vertebral collapse occurs.2,7,8 Abbreviations used in this paper: CT = computerized tomogra- The purpose of this paper is to present the current data phy; GI = gastrointestinal; MMA = methylmethacrylate; MR = concerning surgical treatment of spinal metastatic lesions. magnetic resonance; PMMA = polymethylmethacrylate; VB = ver- Relevant issues concerning evaluation, diagnostic work- tebral body. up, adjunctive preoperative procedures, and surgical tech- Neurosurg. Focus / Volume 11 / December, 2001 1 Unauthenticated | Downloaded 09/28/21 09:58 PM UTC R. F. Heary and C. M. Bono nique are discussed. Effective treatment decision making astatic prostate cancer, Yamashita, et al.,39 reported longer involves the cooperation of patient and family, medical survival in patients with spinal or pelvic lesions (Group I) and radiological oncologists, and the surgical team. compared with those in whom appendicular spread had occurred (Group II). The mean survival time after initia- tion of treatment (of primary cancer) in Group I was 5.7 PATHOPHYSIOLOGY OF METASTATIC years compared with 2.4 years in Group II. The authors DISEASE hypothesized that axial metastasis was more likely in general because of the proximity of the primary tumor to the A primary carcinoma must undergo several steps before Batson venous plexus (vertebral venous system). The Bat- producing a metastasis at a distant site. Common primary son plexus is a valveless venous system that has been fre- cancers that spread to bone are lung, breast, renal, pros- quently implicated as a conduit for the metastatic spread tate, and thyroid. Lung is the most common neoplasm in of prostate tumors. Thus, they found that patients who pre- males, whereas breast is the most frequent in females. sented with vertebral lesions initially harbored the least Despite the anatomical location, the tumor must grow be- aggressive tumor, whereas in those with appendicular le- yond the bounds of the basement membrane of the cells at sions the metastasis had bypassed the Batson plexus. In- the primary (extraspinal) site of the tumor. This process is terestingly, patients with both appendicular and axial met- facilitated by enzymes known as matrix metalloproteinas- astases (Group III) an intermediate life expectancy (3.4 es causing degradation of this layer. Acting most specifi- years) was demonstrated, which was better than Group II cally to break down the Type IV collagen in the basement but worse than Group I.39 membrane, the cancerous growth is then given access to Some investigators have addressed the question of sur- surrounding blood vessels and lymph vessels. Tumor cells vival after surgery for spinal metastatic tumors. Tokuhashi can then travel to distant tissues. For the cell to success- and coworkers37 have studied the results obtained in 64 fully metastasize, it must adhere to the second site and patients who underwent surgery for spinal metastases. obligatorily stimulate the growth of new blood vessels. They included all primary diagnoses and operations per- This is known as tumor angiogenesis. Unfortunately, a formed for a variety of indications including pain and pa- well-vascularized metastasis will survive at the expense of ralysis. They formulated a score based on a number of normal healthy tissue. parameters including general systemic condition, number In the spinal column, metastatic carcinoma has a predil- of extraspinal bone metastases, number of spinal metasta- ection for the well-vascularized cancellous bone of the ses, presence of lesions in other internal organs, location VB. Less frequently, a lesion will develop only in the pos- of the primary lesion, and the severity of spinal cord in- terior elements (that is, the neural arch). In some situa- jury. Although no single parameter was predictive, scores tions, the tumor extends from the the anterior to posterior correlated with survival periods. Scores of 9 or higher columns, making it more difficult to plan a surgical de- were predictive of at least 12 months of survival; scores of bulking or resection of the tumor. 8 and lower indicated survival less than 12 months; and scores of 5 or lower predicted survival of 3 months or less. IMPORTANCE OF SURVIVAL PROGNOSIS Based on these data, it appears that the Tokuhashi system would be a valuable tool in preoperative discussions Patients with metastatic cancer have limited life expec- and decision making. Its value has been confirmed by tancies. After primary lung cancer has spread to distant other authors. Enkaoua, et al.,10 found it predictive of sur- organs, the mean survival time is 6 months. The mean survival after surgery in patients with most metastatic tumors vival after metastasis of breast, renal, or prostate carcino- to the spine. One exception was in cases of tumors of un- ma is less dismal, averaging approximately 1.5 to 2 years. known primary origin. The investigators suggested ascrib- Fewer than 10% of patients with metastatic renal cancer ing a lower score to patients in this group, because their survive more than 2 years.35 Because of recent advances in outcomes were generally poorer than predicted. It has the medical

Load more