Medical terms A–Z

Esophagectomy removes part or all of the esophagus, most often to treat esophageal cancer that has not responded to other therapy alone.

Inflammation of the esophagus (the tube that carries food from the mouth to the stomach).

Examination of the esophagus using an esophagoscope.

A moving X-ray of a swallow, showing not merely the shape of the tube but whether it actually works.

A valve at each end keeps traffic moving one way, and it is failure of the lower one that causes most trouble.

An old, inexpensive blood test that reports something is wrong somewhere without saying what or where.

Essential thrombocythemia is a bone marrow disorder that causes an elevated platelet count without a reactive cause such as infection or iron deficiency.

Essential thrombocytosis describes a persistently elevated platelet count arising from a primary bone marrow disorder rather than a temporary reactive process.

An ester is a chemical compound formed from an acid and an alcohol, a structural class that includes dietary fats and certain local anesthetics.

A form of estrogen that may have fewer side effects than other forms.

A blood estradiol result means little without knowing where in the cycle, or where in life, the sample was taken.

A combination of the hormone estradiol (an estrogen) and nitrogen mustard (an anticancer drug).

After menopause the ovaries largely stop making it, and fat tissue converting adrenal hormones becomes the main remaining source.

A loose label stretched across two unrelated drug strategies: occupying the receptor, or shutting off the supply of the hormone upstream.

A hormone receptor that works as a gene switch, so blocking it changes what a cell builds rather than merely what it senses.

Describes cells that do not have a protein to which the hormone estrogen will bind.

A result that reads like a label but works as a prediction, since it forecasts which treatments a tumor is likely to answer.

A lab test to find out if cancer cells have estrogen receptors (proteins to which estrogen will bind).

Hormones given to postmenopausal women or to women who have had their ovaries surgically removed.

A substance that comes from a type of sea squirt and is being studied in the treatment of cancer.

An injection of ethanol (alcohol) through the skin directly into a tumor to kill cancer cells.

The hard cases are hard because two sound principles point in opposite directions, not because anyone has done something wrong.

A final personal message or document in which a person shares his or her thoughts, values, memories, life lessons, advice, and hopes for the future.

A form of poppy seed oil that contains iodine.

A type of paranasal sinus (a hollow space in the bones around the nose).

The property that sterilizes is the property that harms, since the gas reacts with DNA whether that DNA belongs to a microbe or a person.

A drug that belongs to the family of drugs called bisphosphonates.

Diagnosis names what a condition is; etiology names what produced it, and the two answers can be separated by decades of research.

Eucalyptus oil is a plant derived ingredient added in small amounts to cough drops and chest rubs, though the concentrated oil is toxic if swallowed.

On its own the word describes a mood, not a diagnosis; what matters clinically is what produced it and how long it lasts.

An ultrasound probe carried down the gullet on a scope, close enough to image organs the skin hides.

A procedure to take a sample of tissue for examination under a microscope.

Intention is what the definitions turn on, which is why several superficially similar practices near the end of life are classified separately.

Disease that cannot be measured directly by the size of the tumor but can be evaluated by other methods specific to a particular clinical trial.

Patients whose response to a treatment can be measured because enough information has been collected.

Ewing sarcoma is an aggressive childhood and adolescent cancer of bone or soft tissue, marked by a characteristic chromosomal translocation involving the EWSR1 gene.

Outside of the living body.

Excision is the removal of tissue or a body structure by cutting it out during a procedure.

The whole lump comes out, so the pathologist can judge not only what the cells are but where they stop.

A surgical procedure used to remove moles, cysts, skin cancer, and other skin growths using local anesthesia.

To get rid of waste material from the blood, tissues, or organs by a normal discharge (such as sweat, urine, or stool).

Exenteration is an extensive surgery that removes multiple organs from within a body cavity, most often as treatment for advanced cancer.

A disease in which malignant (cancer) cells are found in the tissues of the pancreas.

A pancreatic cell that produces enzymes that are secreted into the small intestine.

A way to provide an investigational therapy to a patient who is not eligible to receive that therapy in a clinical trial, but who has a serious or life-threatening illness for which other treatments…

A label describing the setting as much as the substance, since an approved drug becomes experimental again in a new disease.

A medicine still being tested in people, obtainable mainly through a trial rather than an ordinary prescription.

Surgery to look inside the body to help make a diagnosis.

Cancer has spread outside of the lung in which it began or to other parts of the body.

A type of radiation therapy that uses a machine to aim high-energy rays at the cancer from outside of the body.

A type of radiation therapy that uses a machine to aim high-energy rays at the cancer from outside of the body.

A procedure in which blood is removed from the body and treated with ultraviolet light and drugs that become active when exposed to light.

Outside of the cranium (bones that surround the brain).

A rare cancer that forms in germ cells in the testicle or ovary, or in germ cells that have traveled to areas of the body other than the brain (such as the chest, abdomen, or tailbone).

An extract is a concentrated preparation drawn from a plant, animal, or microorganism, used either as a medication itself or as an ingredient within one.

An area of the body other than the ovaries or testes.

A rare cancer that develops in germ cells that are found in areas of the body other than the ovary or testicle (such as the brain, chest, abdomen, or tailbone).

Extrahepatic describes structures, findings, or disease processes located outside the liver, as distinguished from those confined within the liver itself.

The part of the common hepatic bile duct (tube that collects bile from the liver) that is outside the liver.

A rare cancer that forms in the part of the bile duct that is outside the liver.

Refers to an area or organ outside of the lymph nodes.

Extraocular describes structures or movements located outside the eyeball itself, such as the muscles that direct eye movement.

Extraosseous findings or tissue occur outside the bone itself, a distinction that matters when a tumor or process could otherwise arise within it.

Surgery to remove a diseased lung, part of the pericardium (membrane covering the heart), part of the diaphragm (muscle between the lungs and the abdomen), and part of the parietal pleura (membrane…

The rarer implantation sites are the difficult ones, being harder to see on a scan and behaving differently from a pregnancy in the tube.

The leakage of blood, lymph, or other fluid, such as an anticancer drug, from a blood vessel or tube into the tissue around it.

Eye cancer includes several distinct cancer types affecting different eye tissues, ranging from pigment producing cells to the retina itself.

A drug used to treat acute lymphoblastic leukemia (ALL).

A radiolabeled substance being studied as an imaging agent in breast cancer.

A substance being studied in the prevention of palmar-plantar erythrodysesthesia (pain, swelling, numbness, tingling, or redness of the palms of the hands or soles of the feet) in breast cancer…

A slender tube through which eggs pass from an ovary to the uterus.

A test result that indicates that a person does not have a specific disease or condition when the person actually does have the disease or condition.

A test result that indicates that a person has a specific disease or condition when the person actually does not have the disease or condition.

It runs through families on a single dominant gene, yet a sizeable share of cases begin with a brand new mutation.

Cancer that occurs in families more often than would be expected by chance.

A condition that runs in certain families in which at least two members have dysplastic nevi (atypical moles) and have a tendency to develop melanoma.

A rare inherited condition in which one or more tumors form in the parathyroid glands (four pea-sized organs found on the thyroid) and cause them to make too much parathyroid hormone.

An inherited form of medullary thyroid cancer (cancer that forms in the cells of the thyroid that make the hormone calcitonin).

Familial polyposis is an inherited disorder causing hundreds of colorectal polyps that carry a near certain lifetime risk of colorectal cancer.

A map of who in a family had what and when, and one of the cheapest risk assessments available in any consultation.

A record of the relationships among family members along with their medical histories.

A type of therapy in which the whole family talks with a professional counselor to solve family problems.

An inherited condition marked by the following: (1) one or more first- or second-degree relatives (parent, sibling, child, grandparent, grandchild, aunt, or uncle) with malignant melanoma; (2) many…

A rare inherited disorder in which the bone marrow does not make blood cells.

A type of radiation therapy that uses tiny particles called neutrons made by a machine called a cyclotron.

Fat necrosis is a benign condition in which damaged fat tissue can form a firm lump that closely mimics cancer on examination and imaging.

Persistent exhaustion that does not fully resolve with rest, fatigue can arise from physical illness, psychological strain, or simply insufficient sleep.

The chemical building block of fats, and the reason one fat behaves so differently from another.

A term used in mammography that refers to the replacement of breast tissue with fatty tissue.

Its remit is wide but not total, since meat and poultry, most supplements and much product advertising sit partly or wholly with other agencies.

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

A condition marked by fever and a lower-than-normal number of neutrophils in the blood.

FEC is a chemotherapy combination of three drugs given together for breast cancer, including disease that has spread or returned.

Inability to hold stool in the rectum.

Color carries most of the information, since bile pigment explains brown, its absence explains pale, and digested blood explains black.

A powdered form of fenretinide that is being studied in the treatment of neuroblastoma.

A moving state rather than a fixed one, since age, illness, surgery and treatment all shift it in either direction.

Fertility is the biological capacity to conceive, shaped by hormonal balance, reproductive organ function, and the quality of eggs or sperm.

A fetus is the developing human organism from the end of the embryonic period until birth, distinct from the earlier embryo stage.

Fever is a rise in body temperature above an individual's normal baseline, usually triggered by infection or another underlying inflammatory process.