Preface Chordoma is a rare, low-grade malignant primary bone tumor that originates from residual chordal cells. It most commonly occurs in the occipital slope and sacrum. Chordoma is locally aggressive, but metastasis to the lungs and other organs is not uncommon. Chordomas arising in the sacrum can become so large that they can cause intestinal obstruction, urinary retention, and even lower extremity motor and sexual dysfunction. Chordomas occur between the ages of 50 and 60, with a lower incidence in adolescents. The male to female ratio is approximately 2:1. Chordomas occur almost exclusively in the median bone, most commonly in the sacrococcygeal region (about 50%), followed by the skull base (about 35%), and about 15% in the active spine (cervical > lumbar > thoracic). Most chordomas involve only the vertebral body. Clinical manifestations Pain is the most common clinical manifestation in patients with chordoma. Pain on flexion and rotation is the most common phenomenon in patients with cervical chordoma. If the tumor compresses the spinal cord, myelopathy may be present. Chordoma of the thoracolumbar spine most typically presents with mechanical pain. In addition to sacrococcygeal pain, manifestations of sacral chordoma may include urinary and fecal dysfunction, abnormal sensation in the saddle area, foot drop, and gait abnormalities. Due to the large space in the pelvic and abdominal cavity, the tumor can gradually progress to be very large, slowly producing symptoms such as urinary retention and constipation over months to years, which are often difficult for the patient to detect. Large tumors can be felt in the buttocks as a mass of transitional tissue. Some patients may have symptoms of sciatica. CT scans provide a clearer picture of the destruction and remodeling of bone in chordoma, with enlarged intervertebral foramina and thinning of the bone cortex being common CT findings. Unlike other tumors, chordoma can involve the intervertebral discs and can extend into adjacent vertebral bodies. Due to the large amount of mucin and cartilage matrix in the tumor tissue, it shows low or equal signal to the adjacent vertebrae on T1-weighted images and equal or high signal on T2-weighted images. The tumor can be moderately to significantly enhanced after contrast. Piezolipid images can reflect the boundaries of the tumor more clearly. Definitive diagnosis of chordoma requires CT-guided puncture biopsy. The principles of treatment can be summarized as follows: (1) insensitivity to chemotherapy; (2) insensitivity to conventional radiotherapy; (3) en bloc or gross total resection + subsequent radiotherapy is the best treatment option. According to the SEER database of 414 chordoma cases between 1973 and 2003, the median survival time after surgery was 75 months, but the survival time after metastasis decreased significantly to 24 months, and the 5-year and 10-year survival rates for en bloc resection + adjuvant radiotherapy were 62-67% and 40-45%, respectively. Chordoma of the spine requires a multidisciplinary and comprehensive approach. Based on current evidence from evidence-based medicine, complete resection of the tumor whenever possible remains the preferred treatment modality. Because of the more aggressive local nature of chordoma, it is important to try to remove the tumor as a whole during surgical resection without allowing any spillover of tumor cells. Only in this way is it possible to achieve a disease-free survival time of 70-84.2 months, which is the best clinical outcome reported worldwide. Since the spine is surrounded by many important tissues and organs such as the spinal cord, nerve roots, large blood vessels, esophagus, organs, and intestines, achieving such an extent of resection is very difficult and requires a very experienced surgical team. Sometimes it is necessary to sacrifice the function of some important organs in order to achieve complete removal of the tumor. For example, the affected nerves have to be severed, resulting in impaired limb movement or urinary and bowel function, etc. This is called “throwing away the cart to save the marshal”, sacrificing quality of life for survival time. Although complete surgical resection is the main treatment modality, when the tumor cannot be extensively resected in its entirety, or cannot be removed at all, it is necessary to rely on radiation therapy. Older textbooks or literature used to say that chordoma was insensitive to radiation therapy, which was in response to previous conventional radiation therapy techniques and lower radiation doses. Due to the proximity of the spine to the spinal cord, the tolerated dose of conventional radiotherapy to the spinal cord is only 45-50 Gy, which is much lower than the dose required for radiotherapy of the tumor. Therefore, the local control rate of tumor is only 0~50% according to the conventional technique. With advances in radiotherapy technology, it is now possible to greatly increase the dose of radiotherapy while avoiding damage to the spinal cord. Recent literature from abroad shows that the overall survival rate at 5 years can be increased to 74.3% using stereotactic radiotherapy or proton radiotherapy techniques. The timing of radiotherapy is best chosen preoperatively to reduce the residual tumor cells during surgery. Because of the increased risk of postoperative wound infection due to high preoperative doses, 19.8-50.4 Gy of radiation therapy can be administered preoperatively, depending on the site, and additional doses can be administered postoperatively to the maximum dose required by the tumor. Surgery 4-5 weeks after preoperative radiotherapy is appropriate in the absence of progressive neurological impairment and can further reduce the risk of postoperative wound infection. Chordoma is insensitive to conventional chemotherapy. Recent studies have found that some chronic leukemia drugs are partially helpful in the control of chordoma. Examples include imatinib, manufactured by Novartis, and lapatinib, manufactured by Glaxo. Research in this area is continuing, so patients should have faith that there will be better drugs or treatments that can cure the tumor in the future.