Genetic susceptibility to brain tumors is a difficult issue to sort out. About 5% of brain tumors may be linked to genetic factors, including the following conditions: Li-Fraumeni syndrome, tuberous sclerosis, neurofibromatosis, Turcot syndrome, nevoid basal cell carcinoma syndrome and von Hippel-Lindau disease.
How do these conditions lead to brain tumors?
In these conditions, people inherit a mutation in a tumor suppressor gene, making it more likely that the individual will develop a tumor at some point. This is because cells with a growth advantage multiply without the control of the tumor suppressor gene, gradually accumulating over time.
In addition to genetic mutations, some brain tumors seem to “cluster” within families. Clustering is usually due to a combination of genetic and environmental factors, which can make it difficult to precisely delineate the causes of such tumors and the specific genes involved. Another reason it is difficult to pinpoint the genes and causes is that there are relatively few brain tumor patients available for study, and the possibility that the interaction of genetic and environmental factors varies between people, groups, ethnicities and geographic areas. In short, there are too many possible variables and too few patients to make a clear determination of cause and effect.
What are other risk factors for brain tumors?
It is important to note that the following lists risk factors for brain tumors, which means they are things that increase a person’s chance of developing a brain tumor. However, they cannot be said to cause brain tumors. Some people with many risk factors never develop brain tumors, while others with no risk factors do develop them. The essential message is that knowing about your risk factors and discussing them with your physician may help you make better health care decisions and lifestyle choices.
Age – Children and older people are more likely to develop brain tumors than others. However they can occur at any age.
Gender – Men develop more brain tumors overall than women. However certain types of brain tumors are more common in women, such as meningiomas.
Environmental exposure – Exposure to toxic chemicals such as pesticides, solvents, rubber and vinyl chloride may increase the risk of brain tumor development. However, there is little scientific evidence proving this link.
Viral exposure – Certain viruses may increase the risk of brain cancers, such as Epstein Barr virus (EBV) and cytomegalovirus (CMV). In research studies on animals, there seems to be a connection between other viruses and brain tumors; however further research is needed to confirm this link.
Electromagnetic exposure – There is much debate about whether exposure to cell phones or power lines increase the risk of brain tumors. Current research has had conflicting results; however the World Health Organization recommends limiting exposure to cell phones.
Ethnicity – Interestingly, in the US, whites are more prone to gliomas and less prone to meningiomas than blacks. People of northern European descent have double the chance of developing brain tumors than the Japanese.
Head injuries – Trauma to the head may be associated with brain tumors, but research studies have had conflicting results. There seems to be a link between head injuries and meningiomas, while no link has been found with gliomas. Seizures and brain tumors are also associated, but it is difficult to know if the tumor causes the seizures, the seizures increase the risk of tumors, or if there is a relationship with anti-seizure medications.
Nitrite exposure – Nitrites are found in cured meats, cigarette smoke, and some cosmetics, and some studies indicate that this exposure may be related to the development of brain tumors. However, more research in this area is needed to confirm the suspected link.
As you can see, there are many, many factors involved in the initiation of brain tumors in addition to genetics. Therefore it may not be possible to determine the exact origin of a particular brain tumor. However, it is still useful to maintain an accurate medical history and family history so that patterns can be found that may be useful. Working with your physician, you can assess your risk and make medical and lifestyle choices that have the potential to reduce your risk of developing a brain tumor.