D-20761: A synthetic luteinizing hormone-releasing hormone (LH-RH) antagonist that suppresses LH and sex steroid levels.

DACA: Acridine carboxamide. A substance that is being studied as an anticancer drug. It belongs to the family of drugs called topoisomerase inhibitors.

Dacarbazine: An anticancer drug that belongs to the family of drugs called alkylating agents.

Daclizumab: A monoclonal antibody that is being studied for treatment of adult T-cell leukemia. Also called dacliximab. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells.

Dactinomycin: An anti-cancer (antineoplastic or cytotoxic) chemotherapy drug. This medication is classified as an alkylating agent.

Dalteparin: A drug that helps prevent the formation of blood clots; it belongs to the family of drugs called anticoagulants.

Danazol: A synthetic hormone that belongs to the family of drugs called androgens and is used to treat endometriosis. It is being evaluated in the treatment of endometrial cancer.

Dark-field microscope: A microscope (device used to magnify small objects) in which objects are lit at a very low angle from the side so that the background appears dark and the objects show up against this dark background.

Daunorubicin: An anticancer drug that belongs to the family of drugs called antitumor antibiotics.

De novo (dih NO-vo): In cancer, the first occurrence of cancer in the body.

Decapeptyl: Belongs to the family of drugs called luteinizing hormone-releasing hormone agonists. Used to block hormone production in ovarian ablation.

Decitabine: An anticancer drug that belongs to the family of drugs called antimetabolites.

Decortication (de-KOR-tih-KAY-shun): Removal of part or all of the external surface of an organ.

Deferoxamine: An iron-chelating agent that removes iron from tumors by inhibiting DNA synthesis and causing cancer cell death. It is used in conjunction with other anticancer agents in pediatric neuroblastoma therapy.

Defibrotide: A drug under study for the prevention of veno-occlusive disease, a rare complication of high-dose chemotherapy and stem cell transplantation in which small veins in the liver become blocked.

Dehydroepiandrosterone: DHEA. A substance that is being studied as a cancer prevention drug. It belongs to the family of drugs called steroids.

Dendritic cell: DCs. A potent antigen presenting cells (APCs) that possess the ability to stimulate naïve T cells.

Dendritic cell vaccine: A vaccine made of antigens and dendritic antigen-presenting cells (APCs).

Dental implant: A small metal pin placed inside the jawbone to mimic the root of a tooth. Dental implants can be used to help anchor a false tooth or teeth, or a crown or bridge.

Deoxycytidine: A drug that protects healthy tissues from the toxic effects of anticancer drugs.

DepoFoam-encapsulated cytarabine: The anticancer drug cytarabine formulated inside small particles of a synthetic lipid material called DepoFoam. This dosage form slowly releases the drug and provides a sustained action.

Depsipeptide: Anticancer drugs obtained from microorganisms.

Derivative: In chemistry, a compound produced from or related to another.

Dermatitis: Inflammation of the skin.

Dermatofibrosarcoma protuberans (DER-ma-toe-FI-bro-sar-KO-ma pro-TOO-ber-anz)er-anz): A type of tumor that begins as a hard nodule and grows slowly. These tumors are usually found in the dermis (the inner layer of the two main layers of tissue that make up the skin) of the limbs or trunk of the body. They can grow into surrounding tissue, but do not spread to other parts of the body.

Dermatologist (der-ma-TAH-lo-jist): A doctor who specializes in the diagnosis and treatment of skin problems.

Dermis (DER-mis): The lower or inner layer of the two main layers of tissue that make up the skin.