What is a Brain Tumor?
Seth Joseffer, M.D., F.A.C.S.
A brain tumor is an abnormal growth of cells. The brain, like all of the other parts of the body is composed of an enormous number of very small cells. Cell division, growth and destruction are tightly controlled by the DNA code within the cell. The body normally controls the rate at which these cells are created and destroyed. Sometimes, due to a defect in the DNA code, the cells start to grow more rapidly and form a separate mass inside the head. There are many different types of brain tumors, and they are generally classified based on the type of tissue in which they started.
Is it cancer?
Patients at the beginning of their treatment are generally told that they have an abnormal MRI, that they have a mass, or that they have a brain tumor. What they want to know is whether it is cancer – is it malignant? It all depends on the type of cell. Tumors in the brain are different than tumors in other areas of the body. Breast cancer, for example, generally causes problems when it is able to leave the breast and go to other areas of the body, such as the liver or lungs. Once it reaches those other sites, it can disrupt the body’s vital functions. Doctors generally refer to tumors as ‘cancerous’ or malignant when they have the ability to travel to other sites in the body.
Brain tumors are different in that they do not typically leave the brain and go to other parts of the body. Whether a type of brain tumor is malignant is determined by how likely it is to continue to grow despite treatment. The most malignant tumors have a very high rate of recurrence, while benign tumors may not progress even without treatment. Tumors in the brain cause problems either by disrupting its function, either by pressing on or infiltrating through areas that are critical for normal function and survival.
How Brain Tumors are Classified?
Brain tumors are also classified based on the type of cells from which they came. Some brain tumors start out as cancer in other parts of the body, such as the lungs, and then travel to the brain. Those are called metastatic tumors, such as metastatic lung cancer. Tumors that arise within the brain itself are called primary brain tumors. The brain is composed of many different types of cells, and each of these different types of cells can cause tumors. Some types of cells can cause both benign and malignant tumors.
What Causes a Brain Tumor?
We do not usually have an explanation for why someone gets a brain tumor. While some types of tumor are clearly linked to environmental exposures, as with lung cancer and smoking, there is no similar explanation for most brain tumors. People are often worried about cell phone use, but there is no convincing evidence to support that belief. Tumors arise when cells lose the regulatory mechanisms that control their growth. This loss of regulation comes from changes in the DNA of the cells. These changes are often created randomly, and we do not usually have an explanation for why it happened to an individual person.