1.What is soft tissue sarcoma? Soft tissue sarcoma (STS) is a group of malignant tumors originating from connective tissues other than bone and cartilage (including mucus, fiber, fat, smooth muscle, synovium, transverse muscle, mesothelium, blood vessels and lymphatic vessels, etc.). Neuroectodermal tumors that originate from the neuroectoderm have similar clinical features to soft tissue tumors and are therefore also classified as soft tissue tumors. The incidence of soft tissue sarcoma is 0.75~1.85/100,000, accounting for about 1% of malignant tumors, which can occur at any age and can appear in all parts of the body, more than 60% in the limbs and buttocks, and also in the head and neck, chest, abdomen, retroperitoneum, etc. The most common are malignant fibrous histiocytoma, synovial sarcoma, liposarcoma, and rhabdomyosarcoma. In children, the incidence of rhabdomyosarcoma is the highest, followed by fibrous sarcoma. 2.What are the clinical manifestations of soft tissue sarcoma? （Soft tissue sarcoma is more common in the body wall of limbs and trunk, more common in the proximal part of limbs than in the distal part, i.e., more common in the thigh than in the calf, more common in the upper arm than in the forearm. (2) Pain: Resting pain (i.e., pain at rest) and nocturnal pain can occur, and if the tumor involves adjacent nerves, pain is the first symptom. If the tumor involves adjacent nerves, pain will be the first symptom. (3) Soft tissue sarcoma around the joints may cause deformity and dysfunction of joints, (4) Soft tissue sarcoma in the abdominal cavity and retroperitoneum may cause intestinal obstruction and ureteral obstruction, (5) If lung metastasis has occurred, there are symptoms such as chest pain and blood clotting. 3.How to diagnose soft tissue sarcoma? The diagnosis of soft tissue sarcoma requires a combination of clinical manifestations, imaging manifestations and pathology. The main symptom of soft tissue sarcoma is local mass. Relying on X-ray alone, the preoperative diagnosis is difficult. In recent years, the development of imaging diagnosis, such as ultrasound, CT, MRI, nuclear scan, PET-CT and other examinations have helped a lot in the preoperative diagnosis. It has an undervalued role in the selection of surgical plan and the assessment of preoperative treatment effect. The main means to obtain preoperative pathology is puncture biopsy, and only for the rare cases where puncture biopsy cannot make a clear diagnosis is incisional biopsy considered. Therefore, soft tissue tumors suspected to be malignant should be biopsied at the bone and soft tissue tumors to obtain a clear preoperative diagnosis. 4.What is the treatment status of soft tissue sarcoma? (1) Surgery: At present, surgery still plays an important role in the treatment of soft tissue sarcoma, but the local recurrence rate of simple surgical resection is high, and the local recurrence rate of simple wide resection is 50%, while the recurrence rate of local resection is as high as 80%. Highly malignant soft tissue sarcoma is prone to distant metastases in the lung and other sites, and even with radical surgery, recurrence and metastasis can occur with poor prognosis. In order to obtain satisfactory tumor margins and reduce the recurrence rate, amputation or complete resection of the involved muscle groups is often required, which seriously affects the quality of life of patients. (2) Radiotherapy: It is an important tool to improve the local control rate of soft tissue sarcoma. Especially for highly malignant soft tissue sarcoma, postoperative radiotherapy can achieve the effect of reducing the recurrence rate. It can be divided into preoperative radiotherapy, postoperative radiotherapy, post-mounted radiotherapy (inter-tissue irradiation, brachytherapy) intraoperative electron beam radiotherapy, particle implantation, which can be used alone or in combination according to the patient’s condition, but there are still debates on the time, mode and complications of radiotherapy giving. (3) Chemotherapy: IFO and ADM are now widely used as first-line drugs for chemotherapy of soft tissue sarcoma, but the remission rate varies for different sarcomas. The main problems in China at present are: ① High recurrence rate after surgery. ②No effective chemotherapy drugs for most sarcomas. ③How to use radiotherapy correctly. ④The rehabilitation of limb function after surgery. 5.What is cryotherapy for soft tissue sarcoma? Cryoablation therapy is an important ablation technique. The cryoprobe is accurately inserted into the tumor tissue under the guidance of CT or ultrasound, and the argon-helium freezing system is activated and cooled to kill the tumor with ultra-low temperature. The basic principle of cryoablation is to rapidly chill the tumor tissue to below -160℃ and then re-temperature it, which can directly cause dehydration and rupture of cancer cells; or destroy the small blood vessels of tumor and cause hypoxia, resulting in the death of tumor cells. The advantages of cryoablation treatment are: (1) local destruction of tumor tissue, less impact on normal tissue, and maximum protection of limb function. (2) Less damage to normal tissues compared with surgery, and can be repeatedly performed. (3) Small trauma (the diameter of cryoprobe is about 2-4mm), quick recovery, and normal activities can be resumed the day after surgery. (4) No toxic side effects of radiotherapy and chemotherapy. (5) For small tumors can achieve the purpose of cure. (6) It can treat tumors that cannot be removed by surgery of adjacent important organs (such as large blood vessels, intestines, ureter). (7) For thoracic, abdominal and retroperitoneal soft tissue sarcomas, multiple open-chest and open-abdomen surgeries can be avoided, which obviously improves the quality of life of patients. (8) Local necrotic tumor tissue can stimulate the body’s immune system and improve the body’s anti-tumor immune function. (9) Freezing has synergistic effect with chemotherapy or radiotherapy. (10) For recurrent soft tissue sarcoma after surgery, cryotherapy can help to improve the local control rate. 6.What is the efficacy of cryotherapy for soft tissue sarcoma? Under the guidance of ultrasound or CT, the cryoprobe can be inserted accurately into the tumor tissue, and the efficacy of local treatment is sure. Meanwhile, for tumors in the abdominal cavity, chest cavity, retroperitoneum, head and neck are often inoperable due to their proximity to important organs, while cryotherapy is less traumatic and can reach the conventional surgical exclusion zone and give active treatment to tumors in special areas. 7.Can other treatments be combined with cryotherapy for soft tissue sarcoma? Cryoablation is an effective treatment for soft tissue sarcoma, but due to the deep location, large size or proximity to important organs of some soft tissue sarcomas, cryoablation is not a complete treatment. Minimally invasive treatments such as intra-tissue radioactive particle implantation and local perfusion chemotherapy in the tumor supply artery can be combined with cryoablation to further control the remaining tumor tissue.