O(6)-benzylguanineA drug that may improve the response of cancer cells to chemotherapy.
oat cellAnother name for small cell lung cancer. The name "oat cell" comes from the fact that the cells look like oats. See also extensive SCLC and limited SCLC.
obatoclax mesylate(oh-BAT-oh-klax MEH-zih-layt) A substance being studied in the treatment of several types of cancer.
obeseHaving an abnormally high, unhealthy amount of body fat.
Obesity(oh-BEE-sih-tee) A condition marked by an abnormally high, unhealthy amount of body fat.
objective improvementAn improvement that can be measured by the health care provider (for example, when a tumor shrinks or there are fewer cancer cells in the blood).
oblimersen(oh-blih-MER-sen) A substance being studied in the treatment of cancer. It may kill cancer cells by blocking the production of a protein that makes cancer…
Observation(OB-ser-VAY-shun) Closely monitoring a patient's condition but withholding treatment until symptoms appear or change.
observational studyA type of study in which individuals are observed or certain outcomes are measured.
obsessive-compulsive disorder(ob-SEH-siv kum-PUL-siv dis-OR-der) An anxiety disorder in which a person has intrusive ideas, thoughts, or images that occur repeatedly, and in which he…
obtundation(ob-tun-DAY-shun) A dulled or reduced level of alertness or consciousness.
occult primary tumor(uh-KULT PRY-mayr-ee TOO-mer) Cancer in which the site of the primary (original) tumor cannot be found.
occult stage non-small cell lung cancer(uh-KULT ... KAN-ser) Cancer cells are found in sputum (mucus coughed up from the lungs), but no tumor can be found in the lung by imaging or…
occupational therapistA health professional trained to help people who are ill or disabled learn to manage their daily activities.
octreotideA drug similar to the naturally occurring growth hormone inhibitor somatostatin.
octreotide scanA type of radionuclide scan used to find carcinoid and other types of tumors. Radioactive octreotide, a drug similar to somatostatin, is injected into a…
ocular melanoma(AH-kyoo-ler MEH-luh-NOH-muh) A rare cancer of melanocytes (cells that produce the pigment melanin) found in the eye. Also called intraocular melanoma.
odds ratio(⦠RAY-shee-oh) A measure of the odds of an event happening in one group compared to the odds of the same event happening in another group.
odorant(OH-deh-runt) A substance that gives off a smell.
ofatumumab(oh-FAT-oo-moo-mab) A monoclonal antibody being studied in the treatment of certain types of B-cell cancers including chronic lymphocytic leukemia (CLL)…
off-labelDescribes the legal use of a prescription drug to treat a disease or condition for which the drug has not been approved by the U.S.
ofloxacinAn antibiotic drug used to treat infection. It belongs to the family of drugs called quinolone antibiotics.
OGFOpioid growth factor. A substance made by the body and in the laboratory. It is being studied in the treatment of cancer.
OGX-011A substance that is being studied as a treatment for cancer. It belongs to the family of drugs called antisense oligonucleotides.
ointment(OYNT-munt) A substance used on the skin to soothe or heal wounds, burns, rashes, scrapes, or other skin problems. Also called unguent.
olanzapine(oh-LAN-zuh-peen) A drug used to treat certain mental disorders. It is also being studied in the treatment of nausea and vomiting caused by some cancer…
olfactory(ol-FAK-tuh-ree) Having to do with the sense of smell.
olfactory system(ol-FAK-tuh-ree SIS-tem) The parts of the body involved in sensing smell, including the nose and many parts of the brain.
olfactory transduction(ol-FAK-tuh-ree tranz-DUK-shun) A series of events in which cells in the nose bind to scent-bearing molecules and send electrical signals to the brain…
oligoastrocytoma(AH-lih-goh-AS-troh-sy-TOH-muh) A brain tumor that forms from both oligodendrocytes and astrocytes, which are types of glial cells (cells that cover and…
Oligodendrocyte(AH-lih-goh-DEN-droh-site) A cell that forms the myelin sheath (a layer that covers and protects nerve cells) in the brain and spinal cord.
oligodendroglial tumor(AH-lih-goh-den-DROH-glee-ul TOO-mer) A rare, slow-growing tumor that begins in oligodendrocytes (cells that cover and protect nerve cells in the brain…
oligodendroglioma(AH-lih-goh-DEN-droh-glee-OH-muh) A rare, slow-growing tumor that begins in oligodendrocytes (cells that cover and protect nerve cells in the brain and…
oligofructose-enriched inulin(AH-lih-goh-FROOK-tose en-RICHT IN-yoo-lin) A substance that is used to improve the health of the digestive system and bones and is being studied in the…
omega-3 fatty acid(oh-MAY-guh-3 ...) A type of fat obtained in the diet and involved in immunity.
omentectomy(oh-men-TEK-toh-mee) Surgery to remove part or all of the omentum.
omentum(oh-MEN-tum) A fold of the peritoneum (the thin tissue that lines the abdomen) that surrounds the stomach and other organs in the abdomen.
omeprazoleA drug that inhibits gastric acid secretion.
Ommaya reservoir(o-MY-a REZ-er-vwahr) A device surgically placed under the scalp and used to deliver anticancer drugs to the fluid surrounding the brain and spinal cord.
ON 01910.NaA substance being studied in the treatment of cancer. It blocks certain proteins that are needed for cell growth and may kill cancer cells. ON 01910.
Oncaspar(ON-kah-spar) A drug used to treat acute lymphoblastic leukemia (ALL). It is a form of the drug asparaginase that is linked to a substance called PEG…
oncogeneA gene that normally directs cell growth. If altered, an oncogene can promote or allow the uncontrolled growth of cancer.
oncologist(on-KAH-loh-jist) A doctor who specializes in treating cancer. Some oncologists specialize in a particular type of cancer treatment.
oncology nurse(on-KAH-loh-jee...) A nurse who specializes in treating and caring for people who have cancer.
oncology pharmacy specialist(on-KAH-loh-jee FAR-muh-see SPEH-shuh-list) A person who works with an oncologist to prepare anticancer drugs.
oncolysate(on-KOL-ih-sate) An extract made from cancer cells.
oncolysis(on-KOL-ih-sis) The lysis (breakdown) of cancer cells. This can be caused by chemical or physical means (for example, strong detergents or high-energy…
oncolytic virotherapy(ON-koh-LIH-tik VY-roh-THAYR-uh-pee) Treatment using an oncolytic virus (a virus that infects and breaks down cancer cells but not normal cells ).
oncolytic virus(ON-koh-LIH-tik VY-rus) A type of virus that infects and lyses (breaks down) cancer cells but not normal cells.
oncolytic virus therapy(ON-koh-LIH-tik VY-rus THAYR-uh-pee) Treatment using an oncolytic virus (a virus that infects and breaks down cancer cells but not normal cells ).
OnconaseA substance being studied in the treatment of cancer. It is a type of ribonuclease enzyme. Also called ranpirnase.
Oncophage(ON-koh-fayj) A vaccine made from a patient's tumor cells that may help the body's immune system find and kill cancer cells.
Oncovin(ON-koh-vin) A drug used to treat acute leukemia. It is used in combination with other drugs to treat Hodgkin disease, non-Hodgkin lymphoma…
ondansetron(on-DAN-seh-tron) The active ingredient in a drug used to treat nausea and vomiting caused by cancer treatment.
ondansetron hydrochloride(on-DAN-seh-tron HY-droh-KLOR-ide) The active ingredient in a drug used to treat nausea and vomiting caused by cancer treatment.
onset of actionThe length of time it takes for a medicine to start to work.
OntakA substance used to treat cutaneous T-cell lymphoma when other treatments have not worked.
ONYX-015A modified cold virus that selectively grows in and destroys certain types of cancer cells and leaves normal cells undamaged.
oophorectomy(oh-oh-foh-REK-toh-mee) Surgery to remove one or both ovaries.
open biopsyA procedure in which a surgical incision (cut) is made through the skin to expose and remove tissues.
open colectomy(... koh-LEK-toh-mee) An operation to remove all or part of the colon through a long incision made in the wall of the abdomen.
open label studyA type of study in which both the health providers and the patients are aware of the drug or treatment being given.
operableDescribes a condition that can be treated by surgery.
ophthalmoscope(off-THAL-mo-skope) A lighted instrument used to examine the inside of the eye, including the retina and the optic nerve.
opiateA drug used to treat pain. It contains opium or a substance made from opium (such as morphine).
Opioid(OH-pee-OYD) A drug used to treat moderate to severe pain. Opioids are similar to opiates such as morphine and codeine, but they do not contain and are…
opioid growth factor(OH-pee-OYD grohth FAK-ter) A substance made by the body and in the laboratory. It is being studied in the treatment of cancer.
opportunistic infectionAn infection caused by an organism that does not normally cause disease. Opportunistic infections occur in people with weakened immune systems.
oprelvekin(oh-PREL-vuh-KIN) A drug used to increase the number of blood cells, especially platelets, in some cancer patients receiving chemotherapy.
OPT-80A substance being studied in the treatment of diarrhea caused by infection with Clostridium difficile (a type of bacteria that can grow without oxygen) in…
optic nerveThe nerve that carries messages from the retina to the brain.
optic pathway glioma(...glee-OH-muh) A rare, slow-growing tumor that usually forms in the optic nerve, optic chiasm, or optic tract.
oral cancer(OR-ul KAN-ser) Cancer that forms in tissues of the lip or mouth. This includes the front two thirds of the tongue, the upper and lower gums, the lining…
oral contraceptive pill(OR-ul KON-truh-SEP-tiv) A pill used to prevent pregnancy. It contains hormones that block the release of eggs from the ovaries.
oral surgeonA dentist with special training in surgery of the mouth and jaw.
orchidectomy(or-kih-DEK-toh-mee) Surgery to remove one or both testicles. Also called orchiectomy.
orchiectomy(or-kee-EK-toh-mee) Surgery to remove one or both testicles. Also called orchidectomy.
oregovomab(oh-reh-GOH-voh-mab) A monoclonal antibody that is being studied in the treatment of ovarian cancer.
organA part of the body that performs a specific function. For example, the heart is an organ.
organelle(OR-guh-NEL) A small structure in a cell that is surrounded by a membrane and has a specific function.
organic food(or-GA-nik â¦) Food produced without the use of man-made fertilizer, drugs that increase growth, or drugs that kill insects, bacteria, or other…
organismA living thing, such as an animal, a plant, a bacterium, or a fungus.
orgasm(OR-ga-zum) The final part of the sex act, which involves contraction of sexual organs and a sudden release of endorphins, leading to a feeling of…
Oriental medicine(OR-ee-EN-tul MEH-dih-sin) A medical system that has been used for thousands of years to prevent, diagnose, and treat disease.
oropharyngeal cancer(or-oh-fuh-RIN-jee-ul KAN-ser) Cancer that forms in tissues of the oropharynx (the part of the throat at the back of the mouth, including the soft palate…
oropharynx(or-o-FAIR-inks) The part of the throat at the back of the mouth. It includes the soft palate, the base of the tongue, and the tonsils.
orthodox medicine(OR-thuh-DOX MEH-dih-sin) A system in which medical doctors and other healthcare professionals (such as nurses, pharmacists, and therapists) treat…
orthotopic(OR-thoh-TOP-ik) In medicine, refers to something that occurs in the normal or usual place in the body.
OSI-774A drug used to treat certain types of non-small cell lung cancer. It is also used together with gemcitabine to treat pancreatic cancer and is being…
OSI-7904LA substance that is being studied in the treatment of cancer. It belongs to the family of drugs called thymidylate synthase inhibitors.