08 Mar What is a Brain Tumor?
At Advanced Neurosurgical Associates, we are frequently asked about brain tumors. Below is a summary explanation to help you to understand a little more about them.
First of all, what is a tumor? A tumor is a mass of tissue that is formed by an accumulation of abnormal cells. Tumor cells continue to grow and form a mass. Ordinarily, the cells in your body age, die, and are replaced by new cells. When something disrupts this process, abnormal cells accumulate, and thus, begins this process of tumor formation.
At ANA, we have wide experience with pediatric brain tumors. Brain tumors are the second most common form of childhood cancer and affect nearly 1,500 to 2,000 children in the United States every year. They are diagnosed most often between the ages of three and eight, but can occur at any age. Twelve to fifteen percent of all childhood brain tumors occur in children under the age of two. For reasons undetermined, childhood brain tumors occur in males more frequently than in females, with a 2:1 ratio. There has also been an unexplained increase in the incidence of brain tumors in infants over the past 20 years. There is wide speculation that this seeming increase is due to earlier diagnosis since the emergence of MRI in the last 10-15 years; however, this does not explain why the increase is seen primarily in males. Once diagnosed, the treatment of brain tumors in these young pediatric patients presents many difficult challenges owing to the nature of the developing brain.
A primary brain tumor is one that originates in the brain and not all primary brain tumors are cancerous. Benign tumors (not cancerous) are not aggressive and normally do not spread to surrounding tissues, although they can be serious and even life threatening. According to the National Brain Tumor Society, of the diagnosed brain tumors in 2012, 63% were benign and 37% malignant.
There are over 120 types of brain and central nervous system tumors. Brain and spinal cord tumors are different for everyone. They form in different areas, develop from different cell types, and may have different treatment options.
There are only a few known risk factors for brain tumors which research has established. Otherwise, the cause is unknown. Children who receive radiation to the head have a higher risk of developing a brain tumor than adults; in addition, people who have certain rare genetic conditions such as neurofibromatosis or Li-Fraumeni syndrome are at risk. But those factors represent only a fraction of the approximately 35,000 new primary brain tumors diagnosed each year. Age is also a risk factor: those over the age of 65 are diagnosed with brain cancer at a rate four times higher than younger people.
Here are basic definitions of commonly used brain tumor terms:
- Benign: The least aggressive type of brain tumor is often called a benign brain tumor. This type of tumor originates from cells within or surrounding the brain, do not contain cancer cells, grow slowly, and typically have clear borders that do not spread into other tissue.
- Malignant: Malignant brain tumors contain cancer cells and often do not have clear borders. They are considered to be life threatening because they grow rapidly and invade surrounding brain tissue.
- Primary: Tumors that start in cells of the brain are called primary brain tumors. Primary brain tumors may spread to other parts of the brain or to the spine, but rarely to other organs. Primary tumors occur in people of all ages, but they are statistically more frequent in children and older adults.
- Metastatic: Metastatic, or secondary brain tumors, begin in another part of the body and then spread to the brain. These tumors are more common than primary brain tumors and are named by the location in which they begin. Although statistics for brain metastases are not readily available, it is estimated that there are more metastatic than primary malignant tumors per year. Metastatic brain tumors are more common in adults than children.
Doctors group brain tumors by grade. The grade of a tumor refers to the way the cells look under a microscope:
- Grade I: The tissue is benign. The cells look nearly like normal brain cells, and they grow slowly.
- Grade II: The tissue is malignant. The cells look less like normal cells than do the cells in a Grade I tumor.
- Grade III: The malignant tissue has cells that look very different from normal cells. The abnormal cells are actively growing (anaplastic).
- Grade IV: The malignant tissue has cells that look most abnormal and tend to grow quickly.
Source: National Cancer Institute