Medical terms A–Z

A small mass of tissue within a gland or organ that carries out the specialized functions of the gland or organ.

Most are found by accident on imaging ordered for something else entirely, and most of those turn out to mean nothing at all.

A substance that is being studied in the treatment of liver cancer.

A mathematical device or model that shows relationships between things.

Named for what it is not, this family of lymphocyte cancers spans many separate diseases with very different growth rates and outlooks.

A group of lung cancers that are named for the kinds of cells found in the cancer and how the cells look under a microscope.

Describes a clinical trial or other experiment in which the researchers know what treatments are being given to each study subject or experimental group.

A clinical study that includes some, but not all, of the eligible patients identified by the researchers during the study registration period.

Lymphoma in which the lymph nodes containing cancer are not next to each other, but are on the same side of the diaphragm (the thin muscle below the lungs that helps breathing and separates the…

A tumor that is found in endocrine tissue but does not make extra hormones.

Cancer that does not begin in the blood or bone marrow.

Morinda citrifolia.

In medicine, it describes a procedure that does not require inserting an instrument through the skin or into a body opening.

In biology, refers to viruses that do not kill infected cells by disrupting their plasma membranes.

Not cancerous.

A disorder of the blood.

Abnormal cells are found in the lower part of the epidermis (the outer layer of the skin).

The commonest cancers in people with pale skin, grouped together by what they are not rather than by what they are.

Having to do with skin cancer that forms in the lower part of the epidermis (the outer layer of the skin) or in squamous cells, but not in melanocytes (skin cells that make pigment).

Cancer that has not spread from the primary site (place where it started) to other places in the body.

A drug that is not an opioid.

A medicine that can be bought without a prescription (doctor's order).

A clinical trial in which the participants are not assigned by chance to different treatment groups.

A group of testicular cancers that begin in the germ cells (cells that give rise to sperm).

A cell (such as a phagocyte or a macrophage) that responds to many antigens, not just one antigen.

A member of the family of vegetables that does not contain starch (sugar molecules joined chemically).

A drug that decreases fever, swelling, pain, and redness.

A drug that decreases the production of sex hormones (estrogen or testosterone) and slows the growth of tumors that need sex hormones to grow.

A nontoxic substance does not produce injury or a poisoning effect at the amount and route of exposure being described.

A chemical made by some nerve cells and in the adrenal gland.

Most of what circulates leaks from sympathetic nerve endings rather than pouring out of the adrenal glands, unlike its better known relative.

The seal vouches for who signed and that they did so willingly; it says nothing whatever about whether the contents are true.

An antibiotic drug used to treat infection.

Licensing sits with the state, so what one nurse practitioner may do alone differs from what another may do elsewhere.

A protein found on the surface of some cancers.

The same enzyme block that relieves pain also strips prostaglandin protection from the stomach lining and from blood flow through the kidney.

A substance that is being studied in the treatment of cancer.

A virus being studied in the treatment of neuroendocrine tumors and other types of cancer.

An evaluation of the size and shape of the nucleus in tumor cells and the percentage of tumor cells that are in the process of dividing or growing.

A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body.

A method of diagnostic imaging that uses very small amounts of radioactive material.

Order is everything: the same few units in a different sequence spell a different protein, or a disease causing mutation.

Keeping DNA behind a membrane is what separates human cells from bacteria, and it lets the cell control which genes are read.

Sensation reduced or absent in an area, which is a different finding from the tingling and pins and needles it is often confused with.

The title covers many levels of training and licensure, and what a nurse may legally do is set by the jurisdiction, not the word.

What one may legally do varies by jurisdiction, so the same credential means independent practice in one place and a supervised role in another.

The defining feature is a continuous nursing presence, which is what separates it from assisted living and from care delivered at home.

A nutraceutical is a food derived product marketed for a health benefit beyond basic nutrition, without meeting the approval standard of a drug.

Food is judged by what the body can pull out of it: energy, building blocks, and the trace substances that keep reactions running.

The chain runs from appetite through digestion to absorption, and illness can break it at any single point along the way.

Structured sessions with a trained professional that translate a medical condition into practical decisions about eating.

Sold as a food rather than as a medicine in many countries, which changes what a maker must demonstrate before a product reaches a shelf.

Because the word itself guarantees nothing, the credential letters after a name carry more information than the title in front of the work.

The active ingredient in a drug used to treat infections caused by fungi (a type of microorganism).

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.