Currently, the treatment of glioma is still based on surgery, supplemented by chemotherapy, radiotherapy and biogene therapy. However, gliomas are usually found in or near important functions of the human brain, and have the characteristics of aggressive growth and poor demarcation with normal brain tissue. Therefore, glioma treatment has always been a difficult problem and one of the important topics of medical research.
In recent years, there have been more and more reports of good results in the treatment of glioma with Gamma Knife, and Gamma Knife as a treatment method has been gaining more and more attention with its high accuracy, safety and low incidence of adverse reactions.
1, the advantages of gamma knife
Gamma rays generally do not cause damage to blood vessels, nerves and brain tissue during the irradiation process, and the irradiation target receives a very high dose, while the edge dose is steeply reduced. This large dose contrast ensures that normal body tissues outside the target are only minimally damaged, and most of the damage can be repaired in time.
The principle of conventional radiotherapy is to use the different sensitivity of tumor tissues and normal tissues to radiation, and adopt the method of small dose fractionated treatment to kill the tumor tissues sensitive to radiation, while the normal tissues can be preserved. Therefore, whole brain radiation therapy is suitable for treating malignant tumors that are sensitive to radiation, while gamma knife is more suitable for lesions of smaller size.
Compared with traditional craniotomy, gamma knife treatment has the following advantages.
①No risk of infection, bleeding, etc.;
②No or very minor postoperative complications;
③ short hospitalization period or even no hospitalization.
2. Indications
①Tumor diameter <30 mm (benign tumor or non-functional lesion diameter <40 mm).
②Tumor is solid on CT or MR, with clear boundary, without serious midline shift and occupational effect.
③The tumor was located in deep brain or important functional area, and the surgical risk was high.
④The patient is too old, in poor general condition or combined with other important organ diseases, difficult to tolerate surgery.
⑤Kamofsky Performance Status (KPS) >60; elderly and frail patients or those with KPS score >50, but in good general condition and without obvious increase in intracranial pressure.
(6) Those who refuse craniotomy.
(7) Those who have recurrence or residual after surgery or radiotherapy.
Research shows that the lower the pathological grade of the tumor, the younger the age of the patient, the higher the KPS score, the smaller the volume of the tumor and the tumor is a single lesion, the longer the survival period of the patient.
3.Treatment options
At present, the gamma knife treatment for glioma mainly adopts two options: single high-dose radiation therapy and fractionated low-dose radiation therapy, the latter mainly for those with large tumor size.
4.Treatment effect and adverse reactions
The results of bulk case statistics show that the median survival time of patients with malignant glioma who were biopsied or tumor resected was 48 weeks, while that of patients with glioblastoma multiforme was only 40.9 weeks. Overall, the use of gamma knife for the treatment of glioma has achieved more satisfactory results in clinical practice. The results of imaging review after 3 months of treatment were considered effective if the imaging review showed more than 50% reduction of the lesion. After 3-6 months of glioma treatment by gamma knife, the imaging review results show that the efficiency is between 40% and 60%, and the median survival time of patients can be increased to 85 weeks, with a six-month survival rate of about 95%, a one-year survival rate of 80%, and a two-year survival rate of about 45%. Low-grade malignant tumors account for 75% to 90% of patients who are still alive 2 years after treatment, and their efficacy is significantly better than that of high-grade patients.
For malignant glioma, there are many reports of gamma knife enhancement therapy after conventional radiotherapy or surgery. There are also reports that the efficacy of malignant glioma may be better after increasing the volume dose.
Adverse effects of gamma knife treatment for glioma are rare, the most common is radiation edema, the incidence of which is inconsistent across the literature, generally <25%; after dehydration and hormone therapy, the majority of patients can be relieved within 1~2 weeks. Some patients may experience headache, dizziness, nausea, short-term memory loss, and worsening of existing symptoms, but they can be relieved relatively quickly. In addition, there is a risk of inducing other tumors after gamma knife treatment, and Yu et al. reported one case of meningioma after gamma knife treatment.
5.Summary and outlook
Glioma as a difficult problem in neurosurgery, although a comprehensive treatment based on surgery is adopted, but its efficacy and prognosis is still unsatisfactory. Gamma knife, whether as the first choice of treatment, or as a post-surgical tumor residual and recurrence of complementary treatment, have achieved more satisfactory recent results, although the long-term results are still no fundamental change, but gamma knife treatment to improve the patient’s symptoms, delay recurrence, prolong life, improve the quality of life, or a great help.