| Background and objective:With the increasing level of diagnosis and treatment of malignant tumors,the incidence of malignant brain metastases has also increased year by year.Brain metastases occur in 20% to 40% of cancer patients.Brain metastases of malignant have become the most common intracranial malignancy in adults now.Among various malignancies,brain metastases occur in approximately 50% of lung cancer patients,followed by approximately 15%-20% of breast cancer patients,10% of melanoma patients,5% of colon cancer patients,and 2%-15% of primary cancers patients whose primary tumor is undetected.The current treatment methods for brain metastatic tumors include: surgical treatment,stereotactic surgery,whole brain radiation therapy,chemotherapy,and targeted therapy.The NCCN guidelines recommend that the whole brain radiation therapy is mainly applicable to patients with more than three brain metastases.Combined whole brain radiotherapy with surgery and stereotactic surgery,brain metastases can be controlled more effectively.Therefore,whole brain radiotherapy plays a major role in the treatment of brain metastases.Cognitive function mainly refers to the process of understanding and knowing something,namely the process of obtaining,organizing and applying knowledge.The impairment of cognitive function after whole brain radiation therapy is the main side effect of whole brain radiotherapy,and it has also become a limiting factor for the widespread application of whole brain radiation therapy.The impairment of cognitive function after whole brain radiotherapy mainly manifests as immediate or delayed verbal memory accompanied with nonverbal memory or not.On the contrary,whole brain radiotherapy does not affect general cognitive function and the quality of life.Memory impairment peak at 4 months after radiotherapy and sustain irreversible damage within a few months to several years after radiotherapy.The main damage caused by whole brain radiation therapy includes axonal injury and disruption of white matter growth.And the damage may affect brain structures which manipulate memory function and neurogenesis,such as the hippocampus.The vascular hypothesis of the etiology of radiation damage suggests that radiotherapy will accelerate atherosclerosis and microvascular pathological changes,resulting in the formation of radioactive mineralized vascular insufficiency and infarct,and that ischemia can cause excessive NMDA stimulation causes excitotoxicity.Memantine is a non-competitive,low-affinity,open-channel blocker whose chemical name is 3,5-dimethyl-1-amino-adamantane hydrochloride,which acts primarily on NMDA receptors.It has been proved that memantine has neuroprotective ability in clinical practice.This study evaluated the cognitive function of 43 patients with whole brain radiotherapy and compared the efficacy and safety of memantine in cognitive function protection of patients with whole brain radiotherapy who memantine was used to or not.Methods:A total of 43 patients with whole brain radiotherapy were treated with radiotherapy to the whole brain for 30 Gy.The experience group was administrated of memantine to the twenty-forth week,while the control group only received radiotherapy.The protection efficacy of cognitive function and adverse events were observed.Results:The average score of MMSE was 26.90±0.340、25.60±0.413(P=0.020)in the twelfth week of the experimental group and control group,and 27.29±0.348、25.31±0.524(P=0.005)in the twenty-fourth week of the two groups,respectively.The major adverse events were alopecia,fatigue,headache and nausea in both of groups and there was no significant difference between the two groups(P>0.05).Conclusion:1.Memantine reduced the decline in cognitive function in patients with whole brain radiotherapy and was well tolerated.2.The study provided a new basis to memantine for the protection of cognitive function,and it also provides a new direction for the study of protection of cognitive function in patients with whole brain radiation therapy. |
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