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Neuro-oncology is the study of brain and spinal cord neoplasms, many of which are (at least eventually) very dangerous and life-threatening (astrocytoma, glioma, glioblastoma multiforme, ependymoma, pontine glioma, and brain stem tumors are among the many examples of these). Among the malignant brain cancers, gliomas of the brainstem and pons, glioblastoma multiforme, and high-grade (highly anaplastic) astrocytoma are among the worst. In these cases, untreated survival usually amounts to only a few months, and survival with current radiation and chemotherapy treatments may extend that time from around a year to a year and a half, possibly two or more, depending on the patient's condition, immune function, treatments used, and the specific type of malignant brain neoplasm. Surgery may in some cases be curative, but, as a general rule, malignant brain cancers tend to regenerate and emerge from remission easily, especially highly malignant cases. In such cases, the goal is to excise as much of the mass (tumor cells) and as much of the tumor margin as possible without endangering vital functions or other important cognitive abilities. ==General information== 1. Primary Tumors of the Central Nervous System Primary brain tumors can occur at any age, from infancy to late in life. These tumors often afflict people during their prime years. Factors such as age, tumor location, and clinical presentation are helpful in differential diagnosis. Most types of primary brain tumors are more common in men with the exception of meningiomas, which are more common in women.〔McAllister, L.D., Ward, J.H., Schulman, S.F., DeAngels, L.M. (2002). ''Practical Neuro-Oncology: A Guide to Patient Care.'' Woburn, MA: Butterworth-Heinemann.〕 2. Metastatic Tumors of the Central Nervous System Cancer spreads to the nervous system by direct invasion, compression, or metastasis. Direct invasion or compression from continuous tissues relates to the proximity of the nervous system to other structures, such as the brachial plexus, lumbosacral plexus, vertebral neuroforamina, base of skull, cranium, and pelvic bones.〔 ;Intracranial Metastasis There are three types of intracranial metastasis: brain metastasis, dural metastasis, and leptomeningeal metastasis. Brain metastasis can be single or multiple and involve any portion of the brain. Metastasis to dural structures generally occurs by hematogenous spread or direct invasion from a contiguous bone. Dural metastases can invade the underlying brain and cause focal edema and associated neurologic symptoms. These processes tend to cause seizures early in the course because of their cortical location. Metastasis to the leptomeninges is an uncommon but well-recognized clinical presentation in cancer patients. Leptomeningeal metastasis most commonly is due to breast, lung, or melanoma primary tumors.〔 ;Skull Metastasis Metastases to the skull are divided into two categories by general site: calvarium and skull base. Metastases to the calvarium usually are asymptomatic. Metastases to the skull base quickly become symptomatic because of their proximity to cranial nerves and vascular structures.〔 ;Spinal Metastasis The spine most often is affected by metastatic disease involving the epidural space. This usually occurs as direct tumor spread from a vertebral body (85%) or by invasion of paravertebral masses through a neuroforamin (10-15%).〔 1. Genetic Syndromes and Risk Factors There multiple hereditary conditions that increase a person's chance of developing brain tumors. 2. Nongenetic Risk Factors Few issues in medicine are as potentially contentious as the suspicion of environmental and occupational causes of cancer, including brain tumors. Prior cranial irradiation is the only risk factor that definitely predisposes to brain tumor formation. Some of the risk factors are ionizing radiation, nonionizing radiation, nitrosamines and industrial chemicals. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Neurooncology」の詳細全文を読む スポンサード リンク
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