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Every year, in the United States alone, about 25 thousand people are diagnosed with primary cancers of the brain or central nervous system, cancers that originate in the central nervous system. Another 200,000 people are diagnosed with brain cancers that originated outside the brain and central nervous system.
About 70% of brain cancers are glioblastomas, metastatic tumors that arise in glial cells, cells that "glue" neurons in the brain together to form organized tissues. Cancerous tumors of the pituitary, the "master gland" of the endocrine system, located in the brain, and of the
Tall people are more likely to develop brain cancers than people of short stature or normal height. Men are more likely than women to develop gliomas, and women are more likely than men to develop other kinds of cancerous brain tumors such as pituitary adenomas and hemangiomas. tumors that develop in the linings of blood vessels in the brain.
The only certain controllable risk factor for glioma is exposure to ionizing radiation. Ironically, exposing the brain to multiple imaging procedures may increase the risk of developing a brain tumor. On the other hand, some factors seem to protect against the development of brain tumors.
What Might Reduce Your Risk of Brain Cancer?
Scientists have been looking for lifestyle choices that might reduce the risk of brain cancer for several decades. The Million Woman Study, conducted in the UK, and the European Prospective Investigation into Cancer and Nutrition, conducted in continental Europe, failed to find a significant protective effect of exercise against the development of cancerous brain tumors.
In the United States, the The National Institutes of Health–American Association of Retired Persons study tracked more than 300,000 subjects and discovered a 35% lower risk of glioma for participants who could remember getting regular exercise when they were between 15 and 18 years old, but the study failed to find protection from getting exercise later in life.
The US National Walkers' and Runners' Health Study recruited participants who not only exercised by walking or running on a regular basis, but who could provide data on how much they exercised, and how vigorously. Participants in the study could describe how far they ran or walked, not just for how much time they ran or walked. This selection factor was critical for the usefulness of the data collected in the study, because the inability to recall exercise routes would have biased the results toward the "null," no-effect interpretation of the data.
The reported the usual miles run per week, and the walkers reported the usual miles walked per week and their usual pace in minutes per mile. The researchers used these data to calculate METs, where 1 MET is the amount of energy usually expended while doing no exercise at all. The volunteers were asked question about lifestyle, weight, height, and diet, and then the researchers monitored the National Death Registry for an average of 11+ years for deaths from brain cancer.