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·         dc   Discontinue. A healthcare professional’s note to discontinue some medication or treatment.

·         DCLG   Director’s Consumer Liaison Group. The National Cancer Institute’s patient/consumer advisory group.

·         DDS   Doctor of Dental Science degree.

·         DEA   Division of Extramural Activities of the National Cancer Institute.

·         DEA   Drug Enforcement Administration of the US Department of Justice.

·         debulk   [dee bulk´]   A surgical procedure to reduce the size of a tumor by removing some portion of it; to remove dead tissue resulting from treatment.

·         decompressive   [dee kom pres´ sive]   Refers to a surgical procedure during which bone, tissue, or tumor is removed to lessen intracranial pressure.

·         dedifferentiate   [dee dif fur en´ she ate]   A mature cell returning to a less mature state.

·         deliver   The method and route used to provide medication, for example, PO (by mouth), IV (intravenous), IM (intramuscular), intrathecal, intratumoral, spinal. Also called drug delivery.

·         demyelination   [dee my linn ay´ shun]   Loss of the myelin sheath of a nerve. The myelin sheath insulates the nerve and its loss interferes with electrical impulses between nerves.

·         dendritic cells  A type of white blood cells that processes new antigens and then primes the immune system by its  interactions with T cells and B cells to stimulate the body’s immune response. density   [den´ sih tee]   The amount of darkness or light in an area of a scan reflects the compactness and density of tissue. Differences in tissue density are the basis for CT and MR scans.

·         dermatitis   [dur ma tie´ tis]   Inflammation of the skin.

·         dermoid cyst   [dur´ moyd • sist]   A cyst is a fluid-filled sac, similar to a balloon filled with water. The dermoid cyst is almost always benign, and more common in the spine than in the brain in adults. The incidence in the brain is greatest in children under the age of ten.

·         descending tract   The bundle of nerves running from the brain to the spinal cord that controls muscles and movement.

·         device, medical   An instrument, machine, implant or similar article that is intended for use in the diagnosis, treatment, or prevention of disease. They can be anything from a thermom-eter to an artificial heart to an at-home pregnancy test.

·         DHHS   US Department of Health & Human Services. This department is the federal government’s principal agency for protecting the health of Americans and providing essential human services. Among its agencies are the National Institutes of Health (NIH), the Food and Drug Administration (FDA), Centers for Medicare & Medicaid Services (CMS), and the Centers for Disease Control (CDC) Also abbreviated HHS.

·         diabetes insipidus   [di ah be´ tez • in sip´ id us]   A problem with water balance in the body that causes excess urine production and great thirst due to pituitary-hypothalamic damage. Diabetes mellitus, which has the same symptoms but is far more common, is due to insufficient insulin production by the pancreas.

·         diagnosis   [die ag no´ sis]   The identity of a disease, decided by its signs and symptoms.

·         dietician   A professional trained in diet and nutrition.

·         differentiate   [dif fur en´ she ate]   The process cells undergo as they mature into normal cells. Differentiated cells are normal cells, have distinctive characteristics, perform specific functions, and are less likely to divide.

·         differentiators   Drugs used to make cancer cells more differentiated (or normal) are called differentiating agents.

·         diffuse   [dif fuse´]   Lacking a distinct border, not localized, spread out.

·         diffuse brain stem glioma   A brain stem glioma that is invasive or poorly delineated. They represent about 60-70% of all brain stem tumors and often have a rapid onset of symptoms. The majority of these tumors are fibrillary or anaplastic gliomas.

·         digestive system, digestive tract   The organs in the body that take in food and turn it into products the body uses to function and stay healthy. Waste products leave the body through bowel movements and urination. The digestive system includes the salivary glands, mouth, esophagus, stomach, liver, pancreas, gallbladder, intestines and rectum.

·         diploid   [dip´ loyd]   A cell having two full sets of chromosomes, the normal number for human cells. Eggs and sperm contain a single set of chromosomes (haploid).

·         diplopia   [dih plo´ pee ah]   Double vision.

·         direct cortical stimulation   A technique using a probe to pass a tiny electrical current to delicately stimulate a specific area of the brain. This causes a visible movement of the corresponding body part. Used to pre-determine the function of critical areas of brain tissue so those areas can be avoided during surgery and more extensive tumor removal can be achieved.

·         distal   [dis´ tull]   Located far from the reference point, the opposite of proximal.

·         DMC   Data Monitoring Committee

·         DMD   Doctor of Dental Medicine degree.

·         DNA   Deoxyribonucleic Acid   [dee oks´ ee rye bow new clay´ ik]   The material which makes up chromosomes and genes.

·         DNR   Do Not Resuscitate.

·         DO   Doctor of Osteopathy degree.

·         DOD   Department of Defense (of the US government).

·         DOE   Department of Energy (of the US government).

·         dose-rate   The quantity of a treatment given over a period of time, e.g., 10cc per hour.

·         double-blind study   A clinical trial where neither the doctor nor the patient knows which drug is being given. In a single-blind study, the patients don’t know which treatment they are receiving but the doctors do.

·         doubling time   The time it takes a cell to complete the cell cycle; the time it takes a cell to produce daughter cells.

·         drug delivery   The method and route used to provide medication, for example, PO (by mouth), IV (intravenous), IM (intramuscular), intrathecal, intratumoral, spinal.

·         drug resistance   Failure of cancer cells to respond to chemotherapy.

·         DSc   Doctor of Science degree.

·         dura mater   [du´ rah • ma´ tur]   The outermost, toughest, and most fibrous of the three membranes (meninges) that cover the brain and spinal cord. See meninges.

·         DVM   Doctor of Veterinary Medicine degree.

·         DX, dx   Diagnosis.

·         dynamic CT or dynamic MRI   CT or MRI combined with measuring the uptake of a contrast dye. Especially useful in showing the growth of new blood vessels around a tumor.

·         dysarthria   [dis ar´ three ah]   Impairment of speech (articulation), caused by damage or disorder of the tongue or speech muscles. A symptom that can indicate pressure on the brain stem or elsewhere in the posterior fossa.

·         dysembryoplastic neuroepithelial tumor   [dis em bree o plas´ tik • nur’ o ep ih thee’ lee al]   A grade I tumor that most commonly occurs in people under the age of twenty. When examined under a microscope, the tumor resembles an oligodendroglioma. Abbreviated DNT.

·         dysfunctional   Working improperly or abnormally.

·         dysphagia   [dis fay´ gee ah]   Difficulty in swallowing or inability to swallow. This symptom usually indicates tumors involving the lower brain stem.

·         dysphasia  [dis fay´ zee ah]   Language disorder. Inability to speak words which one has in mind or to think of correct words, or the inability to understand spoken or written words. Symptom common to tumors of the dominant cerebral hemisphere, particularly the frontal, temporal, and parietal lobes.

·         dysplasia   [dis play´ zee ah]   Cells that are abnormal in size, shape and organization.


·         dyspnea   [disp nee´ ah]   Difficult, painful breathing or shortness of breath.