With the improvement of modern tumor diagnosis technology and treatment methods, the survival rate of malignant tumors has been significantly improved. The increase of tumor incidence and the prolongation of survival with tumor necessarily increase the chance of systemic metastasis of tumor. The most common bone metastasis is lung cancer, followed by breast cancer. Lung cancer, breast cancer, prostate cancer, kidney cancer and thyroid cancer, which account for about 90%, are called “pro-bone tumors”. Therefore, metastatic bone tumors are also known as metastatic cancer of bone. The incidence of bone metastasis increases with the increase of the incidence of so-called “bone-averse” tumors, such as liver cancer, stomach cancer, intestinal cancer and other gastrointestinal malignancies. In 2% of patients, the primary lesion is still difficult to find. Besides lung and liver, the skeletal system is the third common site of tumor metastasis, and more than half of them metastasize to the spine. The vast majority of tumors that metastasize to the spinal site are located outside the spinal canal. Most of the metastases are located anterolaterally or posteriorly to the spinal cord, and rarely posteriorly in the pure sense. Of the entire spine, the lumbar spine is the most common. However, because of the relatively small volume of the thoracic spine, 70% of spinal metastases produce symptoms in the thoracic spine, especially in T4-7. The majority of patients with spinal metastases have spinal pain and neuropathic pain, with 10% of patients having spinal pain as the first symptom. Spinal pain is the first symptom in 10% of patients. 5-10% of patients show symptoms of spinal cord compression. The average survival time for metastatic spinal tumors is 10 months. If spinal cord compression leads to paraplegia and cauda equina symptoms (incontinence), it not only increases the burden of care, but also decreases the quality of life of the patient and shortens the survival time. The average survival time after the development of spinal nerve symptoms is only 3 months. Metastatic tumors in the spine mean that the tumor has spread and is at an advanced stage. No treatment can change the disease regression. The goal of treatment is to control pain and preserve as much neurological function as possible. In general, metastatic tumors of the spine are palliative in nature. The treatment of metastatic bone tumors is a comprehensive one. Since the prognosis is closely related to the nature and biological characteristics of the primary tumor, the treatment of the primary tumor, such as chemotherapy, radiotherapy, and hormone replacement, is particularly important. Diphosphonates and local radiotherapy can control tumor growth and relieve pain. Since the causes of the formation of pain and spinal cord injury include tumor destruction, compression, pathological fractures, and the resulting spinal instability. Therefore, surgical approaches to decompression and immobilization can also serve to control pain and maintain neurological function. So, which patients need surgical treatment and how to perform it is the focus of our discussion below. Purpose of surgery For metastatic tumors of the spine, the main purpose of surgery is, to control pain, maintain and improve nerve and spinal cord function, improve the patient’s quality of survival, and facilitate further treatment and care. Indications for surgery The prognosis of surgical treatment is closely related to the appropriate patient selection. As a palliative treatment, strict control of surgical indications is the guarantee to achieve the surgical purpose. 1. Rapidly progressive or sudden onset of paraplegia. As paraplegia occurs, if not decompressed in time, it can result in complete irreversible paraplegia. This type of patient requires emergency surgery. The spinal cord function should be preserved and restored as much as possible. 2. Spinal instability and pathological fracture dislocation. Instability of the spine can cause pain and the treatment is fixation. Stabilization of the spine can improve neurological symptoms, of which 80-100% of patients can be relieved of pain. In contrast, radiotherapy cannot treat longitudinal compression of the vertebral body. Even for tumors sensitive to radiotherapy (lymphoma, neuroblastoma, spermatocytoma, myeloma), the effect takes several days to appear. Pathological fracture dislocation with potential spinal cord injury. Surgery has a role in preventing further impairment of spinal cord function. 3. Histological diagnosis is unknown. If the diagnosis of spinal metastases is uncertain, they can be treated with diagnostic surgery. The source of the primary tumor is clearly identified so that control of the primary tumor can be implemented. 4.Radiotherapy is ineffective or known radiotherapy insensitive tumor. Surgical counter indications 1. The treatment of spinal tumors is palliative, and spinal radiotherapy is the treatment of choice. The benefits of surgery and the risks of surgery should be balanced. As patients with spinal metastases are in advanced stages of tumor, some have reached cachexia or terminal state. For these patients with severe complications, supportive therapy should be the first priority, while the risk of surgery should be evaluated to determine the patient’s tolerance for surgery. For patients who are estimated to be unable to tolerate surgery, surgical treatment should be used with caution. 2. The average survival time for metastatic tumors of the spine is 10 months. In patients whose survival is not expected to be long, a short life expectancy of less than 3 months is a relative counter-indication for surgery. Although any estimate of survival duration will vary from the clinical, there is a need for an assessment system with actionable results. This assessment system should include a thorough clinical history, physical examination, laboratory and imaging data. The Dutch model scoring system is currently used. Survival is predicted based on the Karnofsky Performance Scale (KPS), the primary focus and the involvement of internal organs. The prognosis was divided into three groups according to the results. group A: total score 0-3, median survival 3 months; group B: total score 4-5, median survival 9 months; group C: total score 6, median survival 18.7 months. 3. For radiotherapy-sensitive lesions such as lymphoma and multiple myeloma, short-term radiotherapy can reduce pain and radiotherapy can provide good local control. Therefore, radiotherapy is preferred for tumors that are known to be sensitive to radiotherapy. 4. If complete paraplegia exceeds 24 hours. Generally spinal cord function cannot be recovered. Therefore, surgical treatment is not necessary. 5.Metastasis of multiple segments. For multi-stage decompression, surgery is traumatic and fixation instruments are difficult to fix. Therefore, surgery needs to be considered carefully for multi-stage transfer. Surgical methods 1.Nerve block For severe sacral pain, nerve root amputation is feasible. Spinal thalamic fasciculotomy and spinal cord fasciculotomy can play a role in pain relief. However, because pain can be effectively controlled by drugs, radiotherapy and other surgical methods, nerve block is not commonly used. 2.Laminectomy Initially, it was hoped that the spinal cord could be reduced by simple laminectomy. After a large number of retrospective studies, it was found that this treatment method was effective in only a small number of patients. With further studies, it was found that there was no significant difference in efficacy between the laminectomy decompression group and the non-surgical group when radiation therapy was added. Since most metastases are located anterolaterally or posteriorly to the spinal cord, they are rarely posterior in the pure sense. Therefore, posterior alone cannot completely decompress the tumor on the spinal cord and nerve roots. Posterior decompression alone can exacerbate spinal instability, especially in patients whose anterior vertebrae have collapsed. The morbidity and mortality rate after laminectomy is 10-15%, and the disability rate can be as high as 35%. Therefore, simple posterior decompression, posterior laminectomy is suitable for few patients. 3, diseased laminectomy, spinal cord decompression and internal fixation. It is most suitable for survival more than 6 months, isolated metastases, slow-growing tumors, and tumors outside the spinal canal. Therefore, breast, thyroid, prostate or kidney cancers are more appropriate compared to melanoma and lung cancer. Experienced surgeons can perform combined anterior and posterior surgery in one stage to perform total vertebral body resection. (1) Anterior approach More than 60% of metastases are located in the anterior vertebral body, and metastases in the posterior adnexa alone are less common. Therefore, it is reasonable and effective to perform resection and decompression of the tumor and internal fixation with bone graft from the anterior side. An incision along one side of the sternocleidomastoid muscle allows exposure of the cervical spine and the anterior T1-T2 vertebral body. Lifting the scapula, or an open thoracic approach can reveal the upper thoracic spine. A transthoracic approach can expose the lower thoracic vertebrae. A combined thoraco-abdominal incision can reveal T11 and T12. A large mairocartilage incision can reveal the upper lumbar vertebrae. (2) Posterior approach The posterior approach allows early detection and identification of the spinal cord; management of posterior lesions, application of posterior strong and long segmental fixation, stabilization of multi-segmental lesions; management of sagittal imbalance and pain due to minor instability. Modified posterior lateral approach,The postero-lateral approach allows access to the posterior portion of the vertebral body. If the tumor is located posteriorly to the vertebral body, especially if the tumor invades the pedicle and spreads to the posterior structures, a transpedicular approach is a common surgical approach. After arthrodesis, the arch is removed and the posterior aspect of the vertebral body is accessed. Bilateral transpedicular root resection allows for total vertebral body resection. However, complications of up to 50% have been reported. In the thoracic spine, a postero-lateral approach with transverse rib resection can be chosen. 4, minimally invasive and endoscopic, including endoscopic assisted spinal decompression, percutaneous vertebroplasty with posterior synovectomy, image-guided minimally invasive tumor resection and spinal reconstruction, and percutaneous pedicle screw fixation. Percutaneous vertebroplasty is a simple procedure. The tumor tissue is obtained from the vertebral lesion through the pedicle and injected with bone cement to increase the strength of the vertebral body and restore some of its height for pain relief. This treatment is less invasive and can be performed under local anesthesia. Percutaneous vertebroplasty is appropriate for patients with osteolytic lesions; intact posterior margins of the vertebral body; severe pain that does not tolerate general anesthesia; no clear signs and symptoms of nerve root compression; and patients for whom other treatments have failed. The main complications include: leakage of bone cement; causing dural compression, or pulmonary embolism, etc. Choice of surgical method The choice of surgical method should be individualized. The choice of surgical method needs to be considered in the context of the patient’s condition. Surgery if aimed at spinal cord decompression. The anterior approach can do the resection of the vertebral body and release the tumor compression from the anterior part of the spinal cord. The posterior approach includes unilateral or bilateral postero-lateral decompression and can do decompression of the peridural sac and nerve roots. Usually, the lesion is located in the vertebral body, causing anterior and anterolateral compression, and the laminectomy is performed through an anterior or anterolateral approach. Lateral lesions can be treated through a posterior lateral incision. Metastases isolated in the posterior lateral structures are rare and can be performed with a laminectomy. If the tumor is located in the extramedullary spinal canal or intramedullary, extensive laminectomy is required. For the cervicocranial joint and lumbosacral region, surgical exposure is invasive and anterior fixation and instrumentation are difficult to place. In these patients, a posterior decompression and fixation may be a better surgical approach. If the tumor involves one or two adjacent vertebrae, an anterior approach is a better approach. This is because. It allows direct decompression and reconstruction with fusion instrumentation. If more than three are adjacent, postero-lateral decompression is often required. combined with posterior fusion. Or a combined anterior-posterior approach. If multiple segments of the spine are involved. It is important to determine the cortical bone density and strength of the vertebral body adjacent to the lesion. If the adjacent vertebral body is osteoporotic, anterolateral decompression followed by anterior fusion may not be possible. For these patients, postero-lateral decompression with placement of posterior instrumentation may be a safe option. Either type of resection decompression can cause instability of the spine. Therefore, internal fixation devices are needed to provide spinal stability. If the life expectancy is long, autogenous bone grafting is a better approach in combination with internal fixation instrumentation. Otherwise, immediate stabilization can be achieved with bone cement.