A brain tumor, or lesion, is a cluster of cells that grows in an abnormally rapid manner. Brain tumors can be broken down into two major categories: primary and metastatic. Primary tumors originate from cells within the brain as a result of genetic, environmental or sometimes unknown factors. They can be benign or malignant, and usually they do not spread to other parts of the body. A metastatic brain tumor is one that has spread to the brain from a cancer that originated elsewhere in the body. Metastatic brain tumors most often have spread from the lung or breast.
Brain tumors are not uncommon. In America, 45,000 primary brain tumors are diagnosed each year, about 15 for every 100,000 people. The incidence of metastatic brain tumors is far higher, with 170,000 cases being diagnosed each year. Of patients with systemic cancer, 15 percent will develop a metastatic brain tumor. During the last two decades, the incidence of brain tumors has increased 22 percent overall and 55 percent in people over 65 years of age.
The cause of most brain tumors is not known. But there are some known risk factors, including:
- High intake of cured meats
- Low intake of vitamins C & E
- Exposure to pesticides or rubber compounds in the workplace
- Low-level radiation exposure
- Inherited diseases, such as neurofibromatosis
A tumor growing within the skull, a restricted and confined space, will inevitably produce symptoms. Increased pressure inside the skull can lead to generalized symptoms that include headache, nausea and vomiting, alteration in consciousness and personality changes. The specific location of the tumor also can cause seizures and can impact motor skills, speech and vision.
The tumor grade, from 1 to 4, refers to the tumor’s aggressiveness, which pathologists can determine by examining the tumor’s cells under a microscope. A Grade 1 tumor is slow-growing and the least malignant. A Grade 4 tumor is the most aggressive and rapidly growing.