Senator Edward M. Kennedy was diagnosed with a type of brain tumor after he experienced a seizure Saturday morning and was brought to Massachusetts General Hospital.

Doctors diagnosed Sen. Kennedy, 76, with a malignant glioma in the left parietal lobe, a region of the brain involved in sensation (such as pain and touch), hearing, reasoning and memory.

Gliomas are abnormal cell masses (tumors) that start in the brain or spinal cord tissue and can spread only within the nervous system.

Though doctors have not released a prognosis for Sen. Kennedy, research suggests patients with malignant gliomas can live from less than a year to five years or more depending on the size, location and severity of the tumor.

About 50 percent of the estimated 17,000 new brain tumors diagnosed each year in the United States are malignant gliomas. Treatment options for malignant gliomas include surgery and a combination of chemotherapy and radiation therapy. In radiation therapy, high-energy X-rays or other types of radiation are used to kill cancer cells and shrink tumors.

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