Do we know what causes brain and spinal cord tumors in adults?
The cause of most brain and spinal cord tumors is not fully understood. But researchers have found some of the changes that occur in normal brain cells that may lead them to form brain tumors.
Normal human cells grow and function based mainly on the information contained in each cell’s chromosomes. Chromosomes are long strands of DNA in each cell. Brain and spinal cord tumors, like other tumors, are caused by changes in the DNA inside cells. DNA is the chemical that makes up our genes — the instructions for how our cells function. We usually look like our parents because they are the source of our DNA. But DNA affects more than how we look.
Some genes control when our cells grow, divide into new cells, and die. Certain genes that help cells grow, divide, and stay alive are called oncogenes. Others that slow down cell division, or cause cells to die at the right time, are called tumor suppressor genes. Cells sometimes make mistakes in copying their DNA when dividing into 2 cells. Cancers can be caused by DNA changes that turn on oncogenes or turn off tumor suppressor genes. These gene changes can be inherited from a parent, but more often they happen during a person’s lifetime.
In recent years, researchers have found the gene changes that cause some rare inherited syndromes (like neurofibromatosis, tuberous sclerosis, Li-Fraumeni syndrome, and von Hippel-Lindau syndrome) and increase the risk of developing some brain and spinal cord tumors. For example, the Li-Fraumeni syndrome is caused by changes in the TP53 tumor suppressor gene. Normally, this gene prevents cells with damaged DNA from growing. Changes in this gene increase the risk of developing brain tumors (particularly gliomas), as well as some other cancers.
In most cases, it is not known why people without inherited syndromes develop brain or spinal cord tumors. Most risk factors for cancer somehow damage genes. For example, tobacco smoke is a risk factor for lung cancer and several other cancers because it contains chemicals that can damage genes. The brain is relatively protected from tobacco smoke and other cancer-causing chemicals that we might breathe in or eat, so these factors are not likely to play a major role in these cancers.
Several different gene changes must usually occur in normal cells before they become cancerous. There are many kinds of brain tumors, each of which may have different sets of gene changes. A number of gene or chromosome changes have been found in different brain tumor types, but there are probably many others that have not yet been found.
Researchers now understand some of the gene changes that occur in different types of brain tumors, but it’s still not clear what causes most of these changes. Some gene changes might be inherited, but most brain and spinal cord tumors are not the result of known inherited syndromes. Other than radiation, there are no known lifestyle-related or environmental causes of brain tumors. Most gene changes are probably just random events that sometimes happen inside a cell, without having an outside cause.
Last Medical Review: 03/05/2014
Last Revised: 03/05/2014