67-6

42/93

tion has been further subdivided, the effective administration of gefitinib has become possible. In other words, patients were not given ineffective drugs, and the medical and economic losses were reduced. A similar case can be seen in glioblastoma, where bevacizumab showed no clear improvement in prognosis for primary glioblastoma as a whole but did improve the prognosis for proneural-type glioblastoma for more than 4 months13).Therefore, it can be said that the nature of brain tumors, especially parenchymal tumors, is defined by genetic abnormalities. However, since the inci-dence of CNS tumors is extremely low and the organs are not suitable for systemic administration of drugs due to the existence of the brain-blood barrier, the development of molecularly targeted drugs is not an area that is actively pursued. However, the prognosis of brain parenchymal tumors is poor. Patients who suffer from so-called WHO grade 3 tumors have only about 3 years of life, and grade 4 tumors have a prognosis of about 1 year, which is extremely poor compared to other cancers14).As mentioned above, some brain tumors have been shown to have abnormalities in multiple signaling pathways associated with abnormalities in tumor suppressor genes.In brain tumor cells, abnormal growth signals are constantly being sent out. Subsequently, the abnormal cells produced by abnormal signals are managed. This means that the defense mechanisms for normal tissue are totally failing. Furthermore, epigenetic anomalies are considered in the mainte-nance of tumor cells14). Fortunately, some brain parenchymal tumors have been found to have genetic abnormalities in common with tumors in other organs, and there is a possibility that molecu-larly targeted drugs developed for tumors in other organs can be used for these tumors9).The cancer genome panel test was developed as a means to identify such common genetic abnor-malities and to select appropriately targeted drugs and has recently become available in Japan under health insurance.This test can examine hundreds of genetic abnor-malities that may be therapeutic target genes at a time and can be performed on excised specimens or blood. This information will be reported to the 550patient after consultation with an expert panel and the patient's physician, which will lead to the selec-tion of appropriate medical care. In addition, the data is collected in the Center for Cancer Genomic and Advanced Therapeutics (C-CAT), which is a national project to collect cancer genome informa-tion in Japan and use it for future treatment15).Considering the purpose of this project, the work of surgeons is expected to change. Surgeons have previously focused on radical resection as their primary goal, but in the future, if there is a good drug, it may be enough to collect a specimen containing enough genetic material to tell us if we should use that drug.There are a few problems with this test. First, it is very expensive, and second, it does not always find the right drug. Only 30% of the patients who underwent this test were able to receive any form of drug treatment16). There is an absolute lack of therapeutic agents available. We need to identify the genetic abnormalities that occur in tumor cells that are directly related to growth, invasion, metas-tasis, etc., and drugs to correct these abnormalities.Brain tumors are difficult to resect radically. On the other hand, tumor type is determined by molec-ular biological properties, and the prognosis is also analogous based on molecular biological proper-ties17). (Table 2) This is where cancer genome medicine can come into its own. However, in my experience, no patient with brain tumor patient has ever found a therapeutic drug from this test.Therefore, the indications for the test should be carefully judged. At this point, it is thought that refractory tumors after the completion of standard treatment and rare tumors for which there is no effective treatment are the indications for the test.For example, it should be an intractable brain tumor in children and also considered to be a brain tumor of the young adult generation.Some pediatric brain tumors are known to express the same genetic abnormality as malignant tumors, such as sarcoma, at a frequency of a few percent18). Fortunately, a drug has recently been developed to suppress this genetic abnormality in sarcomas. The use of this drug in pediatric brain tumors has been reported to inhibit tumor growth for several months.The government has also prepared a system to