Brain Tumors

Primary brain tumors start in the brain and tend to stay in the brain, although they may sometimes spread to other regions of the brain or spine. About 40,000 people in the United States are diagnosed with a primary brain tumor each year, with tumors accounting for 1.3% of all cancers.

Most brain tumors are benign, and usually arise from the meninges (layers of tissue that cover the brain), from nerve sheaths, or from the pituitary gland. Malignant brain tumors generally begin in the glial cells or astrocytes (neuronal supportive tissues) and are called astrocytoma or oligodendroglioma. These tumors can vary in their malignancy, from grade I (best prognosis) to grade IV (worst prognosis). Lymphoma and ependymoma are other tumor types that can appear in the brain.

Most brain tumors are not associated with any risk factors. Instead, abnormalities of genes, called gene mutations, and immunosuppression increase a patient's risk of developing brain tumors.

Brain tumors may be treated with surgical removal, radiation therapy or chemotherapy. Often, a combination of these treatments is used. Surgery may be recommended to remove as much of the tumor as possible without causing morbidity, or to relieve pressure inside the skull. Most brain tumors are not cured by surgery alone and may require high-energy radiation therapy (X-rays or photons) to kill remaining cancer cells.

Different brain tumors require different doses of radiation to control them. Like any other organ in the body, the brain can tolerate a limited amount of radiation. Because high doses of radiation can damage normal tissue, image-based radiation planning is used to deliver high doses to the tumor with the lowest possible dose to the surrounding tissue.

Developments in engineering and technology have made it possible to treat brain tumors with protons. The physical characteristics of protons make it possible to deliver minimal dose to the normal brain tissue on entry into the body, the prescribed dose to the target, and almost no dose beyond the tumor target.