A risk factor is anything that affects your chance of having a medical issue, such as a brain tumor. Although many potential causes have been and are being studied, we are still not sure exactly what causes most brain tumors.
Risk factors can be environmental, such as being exposed to certain chemicals at home or work, eating or not eating certain foods, physical activity level, and/or other lifestyle choices such as tobacco and/or alcohol use. They can also be genetic, or based on the characteristics we inherit from our parents.
Environmental Risk Factors
Many studies have been performed on a number of potential environmental risk factors. Of the many factors studied, only one—exposure to ionizing radiation—has been clearly shown to increase the risk of developing brain tumors. Some studies have shown that a history of allergies as an adult, a mother eating fruits and vegetables during pregnancy, eating fruits and vegetables as a child, and having chicken pox as a child have the potential to decrease the risk of developing brain tumor.
It is important to note that it can be difficult to accurately measure environmental exposure, which means that results across studies can be inconsistent. More studies must be performed before we can be sure that certain environmental factors—cured food consumption (nitrites), cigarette smoking, cell phone use, and residential power line exposure, for example—are true risk factors for brain tumors.
Genetic Risk Factors
Anything that refers to the genes can be called “genetic.” However, only about 5 to 10 percent of all cancer is hereditary (ie, passed down from one generation to another in a family). In cases of hereditary brain tumors, a mutation, or change in the DNA sequence that makes up a specific gene, is passed from grandparent to parent to child.
Most genetic risk factors are not inherited at birth, but actually build up over time as we age. Genes are the operating instructions for the whole body. While most of our genes do their jobs as expected, a small number may become inactive or stop working the way they should. This inactivity or malfunctioning can change the way cells grow, which may eventually lead to the development of a tumor.
Brain tumors can also be associated with changes in the chromosomes. Each normal cell in any human body has 23 pairs of chromosomes. The most common chromosomal changes in brain tumors occur on chromosomes 1, 10, 13, 17, 19, and 22. Changes on chromosomes 1 and 19 are most frequently found in oligodendrogliomas and changes on chromosome 22 are most frequently found in meningiomas.
Concerns about heredity and brain tumors are common. If you are worried about your family history, begin by sharing it with your family doctor. Although routine screening for brain tumors is not currently available (as it is for breast or cervical cancer, for example), unusual symptoms such as headaches or short-term memory loss can be investigated with your family history in mind.
If multiple members of your family have been diagnosed with brain tumors or you have concerns about starting a family, you may want to talk to a genetic counselor. The Cancer Information Service (1-800-422-6237) can help you find a genetic counselor in your area.