Medical terms beginning with O

A drug that may improve the response of cancer cells to chemotherapy.

A substance being studied in the treatment of several types of cancer.

A label drawn from a height and weight calculation rather than a description of a person, which is why person first wording is now preferred.

Major medical bodies classify obesity as a chronic disease, because the body actively defends an enlarged fat store rather than simply holding surplus weight.

An 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).

A measurable response.

A type of study in which individuals are observed or certain outcomes are measured.

Current classifications place it outside the anxiety disorders, in a group of its own alongside hoarding, body dysmorphic disorder and hair pulling.

Blockage of a hollow structure such as the bowel, airway, urinary tract, or a duct, slowing or halting what normally passes through.

A dulled or reduced level of alertness or consciousness.

Cancer in which the site of the primary (original) tumor cannot be found.

Occupation here means any purposeful activity that fills a day, not a job, which is the usual source of confusion about the title.

OCT is an imaging technique that uses light waves to produce cross-sectional pictures of tissue, most familiar as a routine eye exam of the retina.

Redesigning a hormone that survives only minutes into one lasting hours is what turned somatostatin into a usable medicine.

A type of radionuclide scan used to find carcinoid and other types of tumors.

Ocular melanoma is a rare cancer of the pigment producing cells within the eye, most often arising in the middle layer called the uvea.

Not a ratio of risks, though it is read as one constantly, and the gap between the two widens as an outcome becomes common.

An odor is a smell produced when airborne molecules stimulate the olfactory system.

An odorant is any chemical substance capable of stimulating the sense of smell, whether occurring naturally or added intentionally to a product.

Legal, common and often unavoidable: prescribing outside the approved wording is not the same as prescribing without evidence.

The office within the U.S.

A substance that relieves pain and is being studied in the treatment of some types of cancer.

A substance being studied in the treatment of cancer.

The office within the U.S.

The same drug at the same strength acts more strongly here than in a cream, because sealing the skin lets more of it through.

Olfaction is the sensory process that detects airborne chemical molecules in the nose and interprets them as distinct smells.

Olfactory describes the structures and nerve pathways responsible for detecting and processing smell, from the nasal lining to the brain.

The parts of the body involved in sensing smell, including the nose and many parts of the brain.

A series of events in which cells in the nose bind to scent-bearing molecules and send electrical signals to the brain where they are perceived as smells.

A brain tumor that forms from both oligodendrocytes and astrocytes, which are types of glial cells (cells that cover and protect nerve cells in the brain and spinal cord and help them work the way…

A cell that forms the myelin sheath (a layer that covers and protects nerve cells) in the brain and spinal cord.

A rare, slow-growing tumor that begins in oligodendrocytes (cells that cover and protect nerve cells in the brain and spinal cord).

A brain tumor from the cells that insulate nerve fibers, now identified by a pair of genetic changes rather than by appearance alone.

A drug used in cancer prevention.

A type of fat obtained in the diet and involved in immunity.

Omentectomy removes the omentum, a fatty membrane that drapes over the abdominal organs, most often performed during surgery for ovarian or gastrointestinal cancer.

Nicknamed the policeman of the abdomen for the way it migrates toward trouble and wraps around inflammation before it can spread further.

A device surgically placed under the scalp and used to deliver anticancer drugs to the fluid surrounding the brain and spinal cord.

A substance being studied in the treatment of cancer.

A drug used to treat certain medical conditions.

An oncogene is a mutated gene, derived from a normal growth regulating gene, that drives uncontrolled cell division seen in cancer.

Rarely a single doctor working alone, an oncologist is usually one voice on a team that meets together to agree a plan for each case.

One word covering hundreds of separate diseases, oncology holds together because the questions asked of every cancer are broadly the same.

A nurse whose specialty covers the whole arc of cancer care, from giving hazardous drugs safely to managing what they leave behind.

A licensed pharmacist with special training in how to design, give, monitor, and change chemotherapy for cancer patients.

An oncolysate is laboratory material made by breaking open cancer cells, releasing cellular components that can be studied or used to prompt an immune response.

Naming an outcome and not a method, the word covers anything that leaves cancer cells broken open, from a drug to a virus.

Treatment using an oncolytic virus (a virus that infects and breaks down cancer cells but not normal cells ).

Turning an infection into a treatment, where the burst tumor cell matters less than the alarm its debris raises.

Bursting the tumor cell is only half the mechanism; the wreckage left behind shows the immune system what it should be hunting.

A drug used to treat acute leukemia.

How soon a drug starts working, which is a separate question from how strongly it works or how long it lasts.

Oophorectomy is the surgical removal of one or both ovaries, performed for conditions such as ovarian masses, cancer risk, or disease.

An operation to remove all or part of the colon through a long incision made in the wall of the abdomen.

A type of study in which both the health providers and the patients are aware of the drug or treatment being given.

An operation to remove part or all of the prostate gland through an incision in the lower abdomen or perineum (the area between the anus and scrotum).

Surgery to remove part or all of an organ or a tumor and nearby lymph nodes.

Describes a condition that can be treated by surgery.

Ophthalmic describes anything relating to the eye, including its anatomy, diseases, examinations, and medications formulated for eye use.

A doctor who specializes in diagnosing and treating eye problems, including injury and disease.

A handheld light and lens that turns the pupil into a window onto living blood vessels and nerve tissue.

An opiate is a pain-relieving substance derived directly from opium, a narrower category than the broader term opioid, which also includes synthetic drugs.

These drugs do not remove the source of pain; they change how the nervous system registers it, and the other effects follow from that.

An infection caused by an organism that does not normally cause disease.

A drug used to increase the number of blood cells, especially platelets, in some cancer patients receiving chemotherapy.

A substance being studied in the treatment of diarrhea caused by infection with Clostridium difficile (a type of bacteria that can grow without oxygen) in cancer patients.

The place in the brain where some of the optic nerve fibers coming from one eye cross optic nerve fibers from the other eye.

The place in the brain where some of the optic nerve fibers coming from one eye cross optic nerve fibers from the other eye.

The optic nerve carries visual signals from the retina to the brain and is itself considered an extension of brain tissue.

A rare, slow-growing tumor that usually forms in the optic nerve, optic chiasm, or optic tract.

The nerves that travel from the optic chiasm (place in the brain where some of the optic nerve fibers cross) into certain parts of the brain involved in vision.

In medicine, a technique that uses low power light, fiberoptic instruments, and detectors to examine tissue.

Distinct from denial: an accurate grasp of a diagnosis and a hopeful outlook about living with it can sit together.

Oral describes anything relating to the mouth, including its anatomy, medications taken by swallowing, and examinations of the mouth and throat.

A dentist who specializes in surgery of the mouth, face, and jaw.

Oral cancer arises in the tissues of the mouth, most often as squamous cell carcinoma linked to tobacco and heavy alcohol use.

A precisely bounded space rather than a loose word for mouth, which is why the border with the throat matters so much.

Cancer that forms in tissues of the oral cavity (the mouth).

A daily hormone tablet that prevents pregnancy chiefly by keeping the ovary from releasing an egg at all.

A dentist with special training in surgery of the mouth and jaw.

Surgery to remove one or both testicles.

Surgery to remove one or both testicles.

The level of organization between tissue and body system, where several kinds of tissue combine to do one job.

Organic food is grown and processed under defined regulatory standards that restrict synthetic fertilizers, pesticides, and similar inputs used in conventional agriculture.

A biology word that shrinks in the clinic, where the organism almost always means whatever has grown in the culture bottle.

The final part of the sex act, which involves contraction of sexual organs and a sudden release of endorphins, leading to a feeling of pleasure.

Oropharyngeal cancer develops in the back of the throat, including the tonsils and base of tongue, with a growing share linked to HPV infection.

The oropharynx is the middle section of the throat, positioned behind the mouth and connecting the oral cavity to the lower throat and esophagus.

A system in which medical doctors and other healthcare professionals (such as nurses, pharmacists, and therapists) treat symptoms and diseases using drugs, radiation, or surgery.

In medicine, refers to something that occurs in the normal or usual place in the body.

A drug used to treat certain types of non-small cell lung cancer.

A substance being studied in the treatment of cancer.

The concentration of particles dissolved in a fluid.

Water follows salt and sugar rather than the other way around, and most of the body's fluid shifts follow from that one rule.

A chronic condition in which both the breakdown and regrowth of bone are increased.

Calling it wear and tear undersells it, since cartilage cells actively dismantle their own matrix and the bone changes alongside.

A cancer of the bone that usually affects the large bones of the arm or leg.

An osteolytic process breaks down bone tissue faster than the body can rebuild it, often appearing as a darkened area on imaging.

Osteomyelitis is a bone infection that can arise from bloodstream spread, direct injury, or a nearby infected wound such as a diabetic foot ulcer.

A condition in which there is a lower-than-normal bone mass or bone mineral density (the amount of bone mineral contained in a certain amount of bone).