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·         EBRT   External Beam Radiation Therapy. This acronym is used to distinguish the most common type of radiation, as opposed to interstitial radiation (which employs radiation implants), or radiosurgery.


·         echoplanar MRI   This technique produces MRI images in a faster sequence than traditional MRIs. The increased speed permits the tumor’s use of oxygen to be depicted. Also called functional, “real time” or fast MRI.

·         ECOG   Eastern Cooperative Oncology Group. A clinical cooperative group funded by the National Cancer Institute to test new treatments in adult patients.

·         edema   [eh dee´ ma]   Swelling caused by an excess of water.

·         efficacy   [ef´ ih ka see]   Able to achieve the desired results, produce beneficial effects.

·         EGFR  An acronym for epidermal growth factor receptor, a protein found on the surface of some cells and to which epidermal growth factor binds, causing the cells to divide. It is found at abnormally high levels on the surface of many types of cancer cells, so these cells may divide excessively in the presence of epidermal growth factor. Also called epidermal growth factor receptor, ErbB1, and HER1.


·         eloquent [ELO-kwent]  Refers to sections of the brain that control vital functions such as speech, motor functions, and vision. Tumors in the “eloquent areas” of the brain have higher risks, and may require mapping procedures.


·         embolization   [em bol ih zay´ shun]   Used to reduce the amount of blood supply to a tumor, particles are distributed by way of selective catheters to block the flow of blood in specific arteries.


·         embryonal carcinoma   [em bree on’ al • kar sih no’ ma]   A germ cell tumor. Germ cell tumors begin in the cells that give rise to sperm or eggs. They can occur anywhere in the body. Germ cell tumors of the brain most commonly occur in the pineal or suprasellar regions. These tumors typically respond well to chemotherapy or radiation therapy.


·         embryonic   [em bree on´ ik]   Undeveloped, related to the embryo.


·         emesis   [em´ ih sis]   Vomiting.


·         encapsulated   [en kap´ sue lay ted]   Refers to a tumor that is wholly confined to a specific area, surrounded by a capsule. Localized.


·         encephalopathy   [n seff ah lopp´ ah thee]   A loss of function in tissue of the brain; can be due to a wide variety of causes. See leukoencephalopathy.

·         endocrine dysfunction   [en´ doe krin]   With brain tumors, can refer to an increase, decrease or absence of hormone production by the pituitary gland. Symptoms depend on which hormone is affected and whether it is increased or decreased.

·         endocrine system   [en´ doe krin]   The tissues or glands in the body that secrete hormones into the circulatory system.

·         endocrine therapy   [en´ doe krin]   Treatment by removing, blocking or adding hormones. Also called hormone therapy.

·         endocrinologist   A physician trained in diagnosing and treating disorders of hormone-secreting (endocrine) organs. These organs include the thyroid, parathyroid and adrenal glands, the pituitary, the pineal body and the gonads.

·         endoscopy   [en dos´ ko pee]   A procedure using an endoscope. An endoscope is a long, narrow, flexible tube that provides the surgeon with light and visual access as it is inserted and directed to the target area. The neuro-endoscope is particularly useful for surgery involving a ventricle: to correct a malfunctioning shunt; to remove scar tissue blocking a shunt; or to remove intraventricular tumors. It is also useful during cyst removal.

·         enhancement   Use of a dye that makes abnormal tissue more obvious during CT or MRI scans.

·         enteral   [en´ tur al]   Something which enters the body by way of the intestines such as by eating or drinking. When referring to medication, it is the opposite of parenteral, something that bypasses the intestines, e.g., medicine given through a vein.

·         entry criteria   The conditions which must be met for a patient to enroll in a clinical trial. Usually includes the specific types of tumor, previous treatment allowable, age range and overall health requirements.

·         enzyme   [en´ zime]   A protein substance, secreted by certain cells, that stimulates chemical changes in the body without itself being changed. For example, the enzymes produced in the mouth and stomach are crucial for digestion.

·         EORTC   European Organization for Research and Treatment of Cancer. A network of scientists and oncologists in the main cancer research institutions of the EU countries. They conduct clinical trials throughout Europe.

·         eosinophil   [ee o sin´ o fil]   The type of white blood cell (leukocyte) normally filled with granules containing potent chemicals. The chemicals cause inflammatory reactions or allow cells to digest microorganisms such as bacteria.

·         ependymoblastoma   [ep en´ dih moe blas toe´ ma]   A rare, grade IV tumor, most common in children. It might be classified as a PNET (primitive neuroectodermal tumor) by some. See ependymoma.

·         ependymoma   [ep en´ dih moe´ ma]   This tumor arises from the ependymal cells that line the ventricles and central canal of the spinal cord. It represents about 10% of all childhood brain tumors and also occurs in adults.

·         epidemiology   [ep ih dee me ol´ o gee]   The study of the distribution of disease and its impact upon a population, using measures such as incidence, prevalence, or mortality.

·         epidermoid cyst   [ep ih dur´ moyd]   A cyst is a fluid-filled sac, similar to a balloon filled with water. The epidermoid cyst is usually benign, but will slowly recur if not removed completely. It occurs more frequently in the brain than in the spine and is most common in middle-aged adults.

·         epidural   [ep ih dur´ al]   The space between the wall of the spinal canal and the outermost covering (dura mater) of the spinal cord. An epidural injection is given into this space.

·         epilepsy   [ep´ ill ep see]   Recurrent seizures. A seizure is a sudden change in the electrical activity within the brain that causes a wide range of unusual movements, behaviors and sensations.

·         epithelial   [ep ih thee´ lee ul]   Refers to cells that line the internal and external surfaces of the body, including the skin.

·         equipoise   [eh´ kwi poyz]   Uncertainty as to whether a new treatment is effective; the rationale for investigating a new treatment.

·         ER   Emergency Room.

·         ERISA   Employee Retirement Income Security Act of 1974. This act governs employment or union membership benefits, including disability, health, life insurance, pension and severance.

·         erythema   [air ih theme´ ma]   Red, inflamed skin.

·         esophagitis   [ee sof ah ji´ tiss]   Inflammation of the mucous membrane in the esophagus, a sometime side-effect of chemotherapy. One form of mucositis.

·         estrogen receptor   [ess´ tro jen]   A protein found on some cells to which the hormone estrogen will attach.

·         etiology   [ee tee ol´ o gee]   The study of the cause of a disease.

·         evoked potentials    The use of electrodes to measure the electrical activity of nerves. Can be used as a guide during surgical removal of tumors growing around important nerves.

·         exophytic brain stem glioma   [ek so fit´ ik]   A brain stem glioma that grows outward into the fourth ventricle. Symptoms are due to an increase in intracranial pressure caused by blockage of the flow of fluid from the ventricle.

·         external radiation   Radiation therapy that uses a machine to aim high-energy rays at a cancer. Also called external beam radiation.

·         extracerebral   [eks trah seh ree´ bral]   Located outside the cerebral hemispheres.

·         extradural   [eks trah du´ ral]   External (outside) to the dura mater.

·         extramedullary   [eks´ tra med´ you lair ee]   “Extra” means outside. “Medulla” commonly refers to the medulla oblongata or its extension, the spinal cord. In reference to a tumor in the spine, extramedullary means that the tumor is located between the meninges and the surface of the spinal cord.

·         extramural research, Literally, “outside of the wall” (of the National Cancer Institute). Extramural research is proposed and conducted by non-government scientists in laboratories and clinical facilities throughout the country. About two thirds of the NCI budget is devoted to extramural research project funding.

·         extrinsic brain stem glioma   [ek strin´ sik • glee o´ ma]   A brain stem glioma that grows out from the brain stem. These are often focal tumors and most commonly pilocytic astrocytomas or gangliogliomas.