OBJECTIVE: To investigate the efficacy of intracranial tumors treated with multi-method surgery combined with X-knife. METHODS: Seventy patients with intracranial tumors were treated with multi-method surgery for the tumors before X-knife treatment. These included surgical resection, stereotactic aspiration of cystic fluid and stereotactic biopsy; followed by X-knife treatment. RESULTS: Surgical resection and aspiration resulted in a significant reduction in tumor size, and stereotactic biopsy clarified the pathologic type of the tumor. According to the changes of clinical symptoms and tumor size on CT and MRI scans after X-knife treatment, most of the clinical symptoms disappeared and the size of the lesions decreased significantly, while aggravated and enlarged lesions were regarded as ineffective, and in-between were regarded as effective. 54 patients were followed up clinically for a period of 3-50 months, of which 44 were found to have significant effects, 9 were found to have effective effects, and 1 was found to have ineffective effects. Conclusion: Multi-method surgery for intracranial tumors can reduce the size of the lesion, clarify the pathological type of the tumor, and provide a basis for the development of the X-knife treatment plan to improve the efficacy of treatment. X-knife is suitable for the treatment of intracranial tumors with a diameter of less than 3.0 cm, while it is less effective for larger intracranial lesions. From October 1996 to December 2001, our hospital applied the X-knife system of Fischer Company of Germany to 70 cases of intracranial tumors, which were treated with various surgical methods, including surgical resection, stereotactic suction of cystic fluid and stereotactic biopsy, before X-knife treatment. The above methods not only reduced the size of the tumors, but also clarified the pathological types of the tumors, which provided a reference for the formulation of X-knife treatment dosage. After 3-50 months of follow-up observation, the results were good. The results are summarized as follows: Clinical data General data Among the 70 patients in this group, 43 were male and 27 were female; their ages ranged from 7.0 to 79.0 years old, with an average of 42.5 years old. Among them, there were 30 cases of gliomas in different parts of the brain, 2 of which were cystic tumors with size of 3.0-6.0 cm; 7 cases of gliomas in thalamus and basal ganglia, 1 of which was cystic tumor with size of 1.5-4.0 cm; 6 cases of metastatic carcinoma of brain in cerebral hemisphere, 3 of which were cystic tumors with size of 2.0-5.0 cm; 21 cases of meningiomas in different parts of the brain with size of 1.8-5.5 cm; germ cell tumors in pineal region; and 21 cases of meningiomas in different parts of the brain with size of 1.8-5.5 cm. The pathological diagnosis of the tumors was made by post-surgical pathological section and stereotactic biopsy. Treatment and results 49 cases of large gliomas and meningiomas were directly resected under general anesthesia, and only a small portion of the tumors, 1.5-3.0cm in diameter, remained after surgery; 16 cases of smaller solid tumors located in the thalamus, basal ganglia, brainstem, and the posterior part of the third ventricle were stereotactically biopsied under local anesthesia; 4 cases of metastatic carcinoma and 1 case of glioma with cystic degeneration located in the pontine brain were stereotactically operated under local anesthesia. Four patients with metastatic cancer and one patient with cystic degeneration located in the pontine brain underwent stereotactic surgery under local anesthesia to evacuate the cystic fluid to become substantial tumors with diameters of 1.0-2.5 cm. The pathological types of the tumors were clarified in all 70 patients. The patients were treated with X-knife at a dose of 8.0-24 Gy. According to the clinical symptoms and changes in the size of the lesions on CT and MRI scans, most of the clinical symptoms disappeared and the size of the lesions decreased significantly, while aggravated and enlarged lesions were considered ineffective, and in-between were considered effective. 54 patients were clinically followed up for a period of 3 to 50 months. Fifty-four patients received clinical follow-up from 3 to 50 months, of which 44 were found to be effective, 9 were found to be effective, and 1 was found to be ineffective. Discussion At present, scholars at home and abroad agree that the indications for SRS surgery are: 1) intracranial lesions less than 3.0 cm (volume less than 22.5 cm3); 2) lesions located in important functional areas or deeper locations that cannot be surgically eradicated; 3) direct surgical resection may cause serious functional disorders; 4) those who have residual or recurrent lesions after surgery; 5) patients with a good general condition or no symptoms and smaller lesions; 6) patients who are old and frail; 7) patients with no symptoms and no symptoms; and 8) patients with no symptoms. 6) Patients who are old and frail and cannot tolerate the trauma of direct surgical resection [1, 2]. Compared with direct surgery, X-knife has the advantages of low requirements for the patient’s general condition, minimally invasive, low disability and mortality. However, some patients may experience complications after X-knife treatment, including nausea, vomiting, purpura, cerebral edema, etc. In severe cases, intracranial pressure may increase to a life-threatening level and require surgery [3]. It is generally believed that complications are related to the following factors: 1) the volume of the lesion, 2) the size of the dose received, 3) the number of isocenters, 4) the degree of uniformity of the dose distribution, and the dose received by the normal tissues, especially the dose received by the vital tissues [1, 2, 3]. Therefore, in order to improve the therapeutic efficacy of X-knife and reduce complications, it is necessary to strictly grasp the indications for X-knife therapy and formulate a correct treatment plan. Different sizes of collimators should be used for different sizes and volumes of tumors, and different pathological types of tumors should be given the appropriate therapeutic dose. Thus, we proposed the idea of combining multiple methods of surgery with X-knife treatment for intracranial tumors. Under general anesthesia, the larger tumors can be partially resected by direct surgery to reduce the tumor volume, and the residual or recurrent tumors can be treated by X-knife. When X-knife is used to treat larger tumors, the lower the safe dose used, the lower the possibility of controlling the tumor [1, 2]. If the dose is increased, it will increase the damage to the surrounding brain tissue and increase the chance of complications, so it is not appropriate to use X-knife at the beginning of the treatment of these tumors. In direct surgical resection, if the tumor is malignant, it is difficult to perform total resection because of the unclear boundary between the tumor and the surrounding normal brain tissues. Even in the case of intracranial tumors with clear boundaries, some of them cannot be completely resected because of their deep location or close relationship with the surrounding important nerves and blood vessels, resulting in the tumor remaining or recurring after the surgery. For these patients, we used surgical resection to reduce the size of the tumor and then performed X-knife treatment. For 70 patients in this group, 49 cases of large tumors with residual or recurrent tumors were within 3.0cm after surgical resection, and the peripheral dose was 18-25Gy for meningioma on the convex side of the brain, 13-18Gy for glioma, and 15-25Gy for intracranial metastatic carcinoma, and the therapeutic efficacy of the X-knife treatment was significantly improved. Under local anesthesia, stereotactic technology is used to biopsy smaller lesions located in the deep part of the body and determine the pathological type before X-knife treatment. Certain smaller tumors can be difficult to be completely resected by direct surgery or can cause serious functional disorders after surgery due to the deep location of the tumor and its location in important functional areas [4]. These patients are suitable for X-knife treatment, but it is difficult to determine the treatment dose because the optimal treatment plan should be to use different treatment doses for different types of tumors [1]. If the irradiation dose is too high, the surrounding important tissues will be damaged accordingly, and the chances of complications will be high; if the dose is too low, the tumor will recur. We performed stereotactic biopsy on the tumors of 16 patients in our group before X-knife treatment, clarified the pathological types of the tumors, and made corresponding treatment plans for tumors of different natures. The peripheral dose for germ cell tumors in the pineal region was 8-13 Gy, followed by whole brain irradiation and whole spinal cord irradiation, with a total dose of 25-35 Gy; for lymphomas, 10-14 Gy; for craniopharyngiomas, 15-24 Gy; and for brainstem gliomas, the dose ranged from 12 to 18 Gy. Under local anesthesia, the larger cystic tumors were treated with stereotactic suction of cystic fluid to reduce the size of the tumor, and then X-knife treatment was performed. Although the volume of the whole tumor is very large, but the volume of the solid part of the tumor is very small due to the thin wall of the capsule and extensive, direct surgery is very easy to cause bleeding of the surgical wound, but also easy to lead to the damage of the surrounding brain tissues, the surgical efficacy of the operation is poor, if the X-knife treatment is used directly, due to the target point exceeds the range of X-knife treatment and the high-dose area covered by the cystic cavity of the center of the tumor, the thin layer of the tumor on the wall of the solid part of the tumor by the dose is small, and the efficacy of the treatment is also very poor [ 5]. 5]. In our group of 5 patients, we firstly used stereotactic surgery to aspirate the fluid in the cystic cavity, so that the cystic tumor became a substantial tumor, which not only reduced the size of the tumor, but also alleviated the clinical symptoms of the patients due to the reduction of the compression of the lesion on the surrounding brain tissues. The dose of X-knife treatment is selected between 15-25Gy, which is the highest dose of X-knife treatment in the world.