Vaccination: Treatment with a vaccine.

Vaccine: A substance or group of substances meant to cause the immune system to respond to a tumor or to microorganisms, such as bacteria or viruses.

Vaccine adjuvant: A substance added to a vaccine to improve the immune response so that less vaccine is needed.

Vaccinia CEA vaccine: A cancer vaccine containing the carcinoembryonic antigen (CEA) gene.

Vagina (vah-JYE-na): The muscular canal extending from the uterus to the exterior of the body. Also called the birth canal.

Vaginal (birth) canal: Of or having to do with the vagina, the birth canal.

Valganciclovir: An antiviral agent that is being studied as a treatment for AIDS-related cytomegalovirus.

Vas deferens: A coiled tube that carries the sperm out of the testes.

Vascular endothelial growth factor: VEGF. A substance made by made by cells that stimulates new blood vessel formation.

Vasectomy (vas-EK-toe-mee): An operation to cut or tie off the two t off the two tubes that carry sperm out of the testicles.

Venlafaxine: An antidepressant drug that is being evaluated for the treatment of hot flashes in women who have breast cancer.

Ventricles (VEN-trih-kulz): Fluid-filled cavities in the heart or brain.

Video-assisted surgery: Surgery that is aided by the use of a video camera that projects and enlarges the image on a television screen. Also called video-assisted resection.

Vincristine: An anticancer drug that belongs to the family of plant drugs called vinca alkaloids.

Vindesine: An anticancer drug that belongs to the family of plant drugs called vinca alkaloids.

Vinorelbine: An anticancer drug that belongs to the family of plant drugs called vinca alkaloids.

Vinyl chloride (VYE-nil KLO-ride): A substance used in manufacturing plastics. Exposure to vinyl chloride may increase the risk of liver, brain, and lung cancers; lymphoma; and leukemia.

Viral vector: A type of virus used in cancer therapy. The virus is changed in the laboratory and cannot cause disease. Viral vectors produce tumor antigens (proteins found on a tumor cell) and can stimulate an antitumor immune response in the body. Viral vectors may also be used to carry genes that can change cancer cells back to normal cells.

Virl cells: A type of virus used in cancer therapy. The virus is changed in the laboratory and cannot cause disease. Viral vectors produce tumor antigens (proteins found on a tumor cell) and can stimulate an antitumor immune response in the body. Viral vectors may also be used to carry genes that can change cancer cells back to normal cells.

Virtual colonoscopy: A method under study to examine the colon by taking a series of x-rays (called a CT scan) and the cause disease. Viral vectors produce tumor antigens (proteins found on a tumor cell) and can stimulate an antitumor immune response in the body. Viral vectors may also be used to carry genes that can change cancer cells back to normal cells.

Viscotoxin: A member of a group of small proteins produced by mistletoe plants that are able to kill cells and may stimulate the immune system.

Visual pathway glioma: A rare, slow-growing tumor of the eye.

Vital: Necessary to maintain life. Breathing is a vital function.

Vitamin A: A substance used in cancer prevention; it belongs to the family of drugs called retinoids.

Vitamin E: A substance used in cancer prevention; it belongs to the family of drugs called tocopherols.

Vls: A substance used in cancer prevention; it belongs to the family of drugs called tocopherols.

Vitamin K: A nutrient that promotes the clotting of blood.