# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

N-acetylcysteine

An antioxidant drug that may keep cancer cells from developing or reduce the risk of growth of existing cancer.

N-acetyldinaline

A substance that is being studied as an anticancer drug in the treatment of non-small cell lung cancer. Also called CI-994.

naloxone

A substance that is being studied as a treatment for constipation caused by narcotic medications. It belongs to the family of drugs called narcotic antagonists.

nanogram

A measure of weight. One nanogram weighs a billion times less than one gram, and almost a trillion-times less than a pound.

nanotechnology (NA-noh-tek-NAH-luh-jee)

The field of research that deals with the engineering and creation of things from materials that are less than 100 nanometers (one-billionth of a meter) in size, especially single atoms or molecules. Nanotechnology is being studied in the detection, diagnosis, and treatment of cancer.

narcotic

An agent that causes insensibility or stupor; usually refers to opioids given to relieve pain.

nasal

By or having to do with the nose.

nasopharyngeal cancer (NA-zoh-fuh-RIN-jee-ul KAN-ser)

Cancer that forms in tissues of the nasopharynx (upper part of the throat behind the nose). Most nasopharyngeal cancers are squamous cell carcinomas (cancer that begins in flat cells lining the nasopharynx).

nasopharynx (NA-zoh-fayr-inx)

The upper part of the throat behind the nose. An opening on each side of the nasopharynx leads into the ear.

nasoscope

A thin lighted tube used to examine the nose. Also called a rhinoscope.

nasoscopy

A procedure in which a thin, lighted tube is inserted into the nose to look for abnormal areas. Also called rhinoscopy.

National Cancer Institute

NCI. The National Cancer Institute, part of the National Institutes of Health of the United States Department of Health and Human Services, is the Federal Government's principal agency for cancer research. NCI conducts, coordinates, and funds cancer research, training, health information dissemination, and other programs with respect to the cause, diagnosis, prevention, and treatment of cancer. Access the NCI Web site at http://cancer.gov.

National Institutes of Health

NIH. The National Institutes of Health, the focal point of biomedical research in the United States, conducts research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the NIH Web site at http://www.nih.gov.

natural killer cell

NK cell. A type of white blood cell that contains granules with enzymes that can kill tumor cells or microbial cells. Also called a large granular lymphocyte.

nausea

A feeling of sickness or discomfort in the stomach that may come with an urge to vomit. Nausea is a side effect of some types of cancer therapy.

NB1011

A substance that is being studied for its ability to make cancer cells respond to drugs to which they have become resistant. It belongs to the family of drugs called nucleoside analogs.

NBI-3001

A substance that is being studied in the treatment of cancer. It is made by combining interleukin 4 with a bacterial toxin, and belongs to the family of drugs called recombinant chimeric proteins. Also called interleukin-4 PE38KDEL immunotoxin and interleukin-4 PE38KDEL cytotoxin.

N-butyl-N-(4-hydroxybutyl) nitrosamine

A substance that is used in cancer research to cause bladder tumors in laboratory animals. This is done to test new diets, drugs, and procedures for use in cancer prevention and treatment.

NCI

National Cancer Institute. NCI, part of the National Institutes of Health of the United States Department of Health and Human Services, is the Federal Government's principal agency for cancer research. NCI conducts, coordinates, and funds cancer research, training, health information dissemination, and other programs with respect to the cause, diagnosis, prevention, and treatment of cancer. Access the NCI Web site at http://cancer.gov.

nebulizer

A device used to turn liquid into a fine spray.

neck dissection (dye-SEK-shun)

Surgery to remove lymph nodes and other tissues in the neck.

necrosis (ne-KRO-sis)

Refers to the death of living tissues.

needle biopsy

The removal of tissue or fluid with a needle for examination under a microscope. Also called fine-needle aspiration.

needle-localized biopsy

A procedure that uses very thin needles or guide wires to mark the location of an abnormal area of tissue so it can be surgically removed. An imaging device is used to place the wire in or around the abnormal area. Needle localization is used when the doctor cannot feel the mass of abnormal tissue.

negative axillary lymph node

A lymph node in the armpit that is free of cancer.

negative test result

A test result that fails to show the specific disease or condition for which the test was being done.

nelarabine

A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called antimetabolites. Also called 506U78.

nelfinavir mesylate

A drug that interferes with the ability of a virus to make copies of itself.

neoadjuvant therapy (NEE-o-AD-joo-vant)

Treatment given before the primary treatment. Examples of neoadjuvant therapy include chemotherapy, radiation therapy, and hormone therapy.

neoplasia (NEE-o-PLAY-zha)

Abnormal and uncontrolled cell growth.

neoplasm

An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Tumors may be benign (not cancerous), or malignant (cancerous). Also called tumor.

neoplastic meningitis

A condition in which cancer cells spread into the meninges (membranes that surround the brain and spinal cord).

nephrectomy (neh-FREK-tuh-mee)

Surgery to remove a kidney or part of a kidney. In a partial nephrectomy, part of one kidney or a tumor is removed, but not an entire kidney. In a simple nephrectomy, one kidney is removed. In a radical nephrectomy, an entire kidney, nearby adrenal gland and lymph nodes, and other surrounding tissue are removed. In a bilateral nephrectomy, both kidneys are removed.

nephrologist (neh-FROL-uh-jist)

A doctor who specializes in diagnosing and treating kidney disease.

nephrostomy (neh-FROS-tuh-mee)

Surgery to make an opening from the outside of the body to the renal pelvis (part of the kidney that collects urine). This may be done to drain urine from a blocked kidney or blocked ureter into a bag outside the body. It may also be done to look at the kidney using an endoscope (thin, lighted tube attached to a camera), to place anticancer drugs directly into the kidney, or to remove kidney stones.

nephrotomogram (nef-ro-TOE-mo-gram)

A series of x-rays of the kidneys. The x-rays are taken from different angles and show the kidneys clearly, without the shadows of the organs around them.

nephrotoxic

Poisonous or damaging to the kidney.

nephroureterectomy

Surgery to remove a kidney and its ureter. Also called ureteronephrectomy.

nerve

A bundle of fibers that receives and sends messages between the body and the brain. The messages are sent by chemical and electrical changes in the cells that make up the nerves.

nerve block

A procedure in which medicine is injected directly into or around a nerve or into the spine to block pain.

nerve cell

A type of cell that receives and sends messages from the body to the brain and back to the body. The messages are sent by a weak electrical current. Also called a neuron.

nerve grafting

Replacing a damaged nerve with a section of a healthy nerve that has been removed from another part of the body. This procedure is being studied in the prevention of erectile dysfunction in men having surgery for prostate cancer.

nerve-sparing radical prostatectomy

Surgery to remove the prostate in which an attempt is made to save the nerves that help cause penile erections.

nerve-sparing surgery (SER-juh-ree)

A type of surgery that attempts to save the nerves near the tissues being removed.

Neulasta (noo-LA-stuh)

A drug used to increase numbers of white blood cells in patients who are receiving chemotherapy. It belongs to the family of drugs called colony-stimulating factors. Also called pegfilgrastim and filgrastim-SD/01.

neural

Having to do with nerves or the nervous system, including the brain and the spinal cord.

neurobehavioral

Having to do with the way the brain affects emotion, behavior, and learning. Some cancers or their treatment may cause neurobehavioral problems.

neuroblastoma

Cancer that arises in immature nerve cells and affects mostly infants and children.

neurocognitive

Having to do with the ability to think and reason. This includes the ability to concentrate, remember things, process information, learn, speak, and understand.

neuroectodermal tumor

A tumor of the central or peripheral nervous system.

neuroendocrine (NOO-ro-EN-do-krin)

Having to do with the interactions between the nervous system and the endocrine system. Neuroendocrine describes certain cells that release hormones into the blood in response to stimulation of the nervous system.

neuroendocrine tumor

A tumor derived from cells that release a hormone in response to a signal from the nervous system. Some examples of neuroendocrine tumors are carcinoid tumors, islet cell tumors, medullary thyroid carcinoma, and pheochromocytoma. These tumors secrete hormones in excess, causing a variety of symptoms.

neuroepithelial

Having to do with tissue made up of sensory cells, such as tissue found in the ear, nose, and tongue.

neurofibroma

A benign tumor that develops from the cells and tissues that cover nerves.

neurofibromatosis type 1

NF1. A rare genetic condition that causes brown spots and tumors on the skin, freckling in skin areas not exposed to the sun, tumors on the nerves, and developmental changes in the nervous system, muscles, bone, and skin.

neurofibromatosis type 2

NF2. A genetic condition in which tumors form on the nerves of the inner ear and cause loss of hearing and balance. Tumors may also occur in the brain and on nerves in the skull and spinal cord, and may cause loss of speech, eye movement, and the ability to swallow. Also called acoustic neurofibromatosis.

neurologic (noor-uh-LOJ-ik)

Having to do with nerves or the nervous system.

neurological exam

A series of questions and tests to check brain, spinal cord, and nerve function. The exam checks a person's mental status, coordination, ability to walk, and how well the muscles, sensory systems, and deep tendon reflexes work.

neurologist (noo-ROL-o-jist)

A doctor who specializes in the diagnosis and treatment of disorders of the nervous system.

neuroma (noo-RO-ma)

A tumor that arises in nerve cells.

neuron

A type of cell that receives and sends messages from the body to the brain and back to the body. The messages are sent by a weak electrical current. Also called a nerve cell.

neuro-oncologist (NOO-ro-on-KOL-o-jist)

A doctor who specializes in diagnosing and treating brain tumors and other tumors of the nervous system.

neuropathologist

A pathologist who specializes in diseases of the nervous system. A pathologist identifies disease by studying cells and tissues under a microscope.

neuropathy

A problem in peripheral nerve function (any part of the nervous system except the brain and spinal cord) that causes pain, numbness, tingling, swelling, and muscle weakness in various parts of the body. Neuropathies may be caused by physical injury, infection, toxic substances, disease (e.g., cancer, diabetes, kidney failure, or malnutrition), or drugs such as anticancer drugs. Also called peripheral neuropathy.

neuropeptide

A member of a class of protein-like molecules made in the brain. Neuropeptides consist of short chains of amino acids, with some functioning as neurotransmitters and some functioning as hormones.

neuroradiologist

A doctor trained in radiology who specializes in creating and interpreting pictures of the nervous system. The pictures are produced using forms of radiation, such as x-rays, sound waves, or other types of energy.

neurosurgeon (NOO-ro-SER-jun)

A doctor who specializes in surgery on the brain, spine, and other parts of the nervous system.

neurotoxicity

The tendency of some treatments to cause damage to the nervous system.

neurotoxin

A substance that is poisonous to nerve tissue.

neurotropism

An ability to invade and live in neural tissue. This term is usually used to describe the ability of viruses to infect nerve tissue.

neutropenia

An abnormal decrease in the number of neutrophils, a type of white blood cell.

neutrophil (NOO-tro-fil)

A type of white blood cell.

nevoid basal cell carcinoma syndrome (NEE-voyd BAY-sul cell KAR-sih-NOH-muh...)

A genetic condition that causes unusual facial features and disorders of the skin, bones, nervous system, eyes, and endocrine glands. People with this syndrome have a higher risk of basal cell carcinoma. Also called Gorlin syndrome and basal cell nevus syndrome.

nevus (NEE-vus)

A benign growth on the skin, such as a mole. A mole is a cluster of melanocytes and surrounding supportive tissue that usually appears as a tan, brown, or flesh-colored spot on the skin. The plural of nevus is nevi (NEE-vye).

NF1

Neurofibromatosis type 1. A rare genetic condition that causes brown spots and tumors on the skin, freckling in skin areas not exposed to the sun, tumors on the nerves, and developmental changes in the nervous system, muscles, bone, and skin.

NG-monomethyl-L-arginine

An amino acid derivative used to counteract high blood pressure caused by interleukin-2.

NGR-TNF

A substance that is being studied in the treatment of cancer. It is made by linking tumor necrosis factor (TNF) to a peptide. The peptide binds to tumor blood vessels, and TNF damages them. It belongs to the family of drugs called biological response modifiers. Also called tumor vasculature-targeted tumor necrosis factor alpha.

NHL

Non-Hodgkin's lymphoma. Any of a large group of cancers of the immune system. NHLs can occur at any age, and are often marked by enlarged lymph nodes, fever, and weight loss. There are many different types of NHL, and they can be divided into aggressive (fast-growing) and indolent (slow-growing) types, and are classified as either B-cell or T-cell NHL. B-cell NHLs include Burkitt's lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, precursor B-lymphoblastic lymphoma, and mantle cell lymphoma. T-cell NHLs include mycosis fungoides, anaplastic large cell lymphoma, and precursor T-lymphoblastic lymphoma. Lymphomas related to lymphoproliferative disorders following bone marrow or stem cell transplantation are usually B-cell NHLs. Prognosis and treatment depend on the stage and type of disease.

niacinamide

A vitamin being studied to increase the effect of radiation therapy on tumor cells. Also called nicotinamide.

Nicotiana tabacum

Tobacco. A plant with leaves that have high levels of the addictive chemical nicotine. The leaves may be smoked (in cigarettes, cigars, and pipes), applied to the gums (as dipping and chewing tobacco), or inhaled (as snuff). Tobacco leaves also contain many cancer-causing chemicals, and tobacco use and exposure to secondhand tobacco smoke have been linked to many types of cancer and other diseases.

nicotinamide

A vitamin being studied to increase the effect of radiation therapy on tumor cells. Also called niacinamide.

nicotine (NIH-kuh-TEEN)

An addictive, poisonous chemical found in tobacco. It can also be made in the laboratory. When it enters the body, nicotine causes an increased heart rate and use of oxygen by the heart, and a sense of well-being and relaxation. It is also used as an insecticide.

nicotine gum (NIH-kuh-TEEN.)

A chewing gum that contains a small dose of nicotine, which enters the blood by being absorbed through the lining of the mouth. This helps stop nicotine cravings and relieves symptoms that occur when a person is trying to quit smoking. A prescription is not needed for nicotine gum.

nicotine nasal spray (NIH-kuh-TEEN NAY-zul.)

A nose spray that contains a small dose of nicotine, which enters the blood by being absorbed through the lining of the nose. This helps stop nicotine cravings and relieves symptoms that occur when a person is trying to quit smoking. A prescription is needed for nicotine nasal spray.

nicotine patch (NIH-kuh-TEEN...)

A patch that sticks on the skin and contains a small dose of nicotine, which enters the blood by being absorbed through the skin. This helps stop nicotine cravings and relieves symptoms that occur when a person is trying to quit smoking. A prescription is not needed for nicotine patches.

nicotine replacement therapy (NIH-kuh-TEEN rih-PLAYS-munt THAYR-uh-pee)

A type of treatment that uses special products to give small, steady doses of nicotine to help stop cravings and relieve symptoms that occur when a person is trying to quit smoking. These products include nicotine gum, nicotine inhaler, nicotine nasal spray, nicotine lozenges, and nicotine patch. They do not contain any of the other chemicals found in tobacco products.

NIH

National Institutes of Health. NIH, the focal point of biomedical research in the United States, conducts research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the NIH Web site at http://www.nih.gov.

nilutamide (nye-LOO-ta-mide)

A drug that blocks the effects of male hormones in the body. It belongs to the family of drugs called antiandrogens.

nimodipine

Belongs to a family of drugs called calcium channel blockers. It is being investigated for use with anticancer drugs to prevent or overcome drug resistance and improve response to chemotherapy.

nipple

In anatomy, the small raised area in the center of the breast through which milk can flow to the outside.

nipple discharge

Fluid coming from the nipple.

nitric acid

A toxic, corrosive, colorless liquid used to make fertilizers, dyes, explosives, and other chemicals.

nitrocamptothecin

An alkaloid drug belonging to a class of anticancer agents called topoisomerase inhibitors.

nitrosourea (nye-TRO-so-yoo-REE-ah)

An anticancer drug that can cross the blood-brain barrier. Carmustine and lomustine are nitrosoureas.

NK cell

Natural killer cell. A type of white blood cell that contains granules with enzymes that can kill tumor cells or microbial cells. Also called a large granular lymphocyte.

NMRI

Nuclear magnetic resonance imaging (NOO-klee-er mag-NET-ik REZ-o-nans IM-a-jing). 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. These pictures can show the difference between normal and diseased tissue. NMRI makes better images of organs and soft tissue than other scanning techniques, such as CT or x-ray. NMRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. Also called magnetic resonance imaging (MRI).

node-negative

Cancer that has not spread to the lymph nodes.

node-positive

Cancer that has spread to the lymph nodes.

nodular parenchyma

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

nodule (NOD-yool)

A growth or lump that may be cancerous or noncancerous.

nolatrexed

A substance that is being studied in the treatment of liver cancer. It belongs to the family of drugs called thymidylate synthase inhibitors. Also called AG337 and Thymitaq.

nomogram (NAH-moh-GRAM)

A mathematical device or model that shows relationships between things. For example, a nomogram of height and weight measurements can be used to find the surface area of a person, without doing the math, to determine the right dose of chemotherapy. Nomograms of patient and disease characteristics can help predict the outcome of some kinds of cancer.

nonblinded

Describes a clinical trial or other experiment in which the researchers know what treatments are being given to each study subject or experimental group. If human subjects are involved, they know what treatments they are receiving.

nonconsecutive case series

A clinical study that includes some, but not all, of the eligible patients identified by the researchers during the study registration period. This type of study does not usually have a control group.

noncontiguous lymphoma (non-kun-TIG-yoo-us lim-FOH-muh)

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 chest from the abdomen).

nonhematologic cancer

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

non-Hodgkin's lymphoma (non-HOJ-kinz lim-FOH-muh)

NHL. Any of a large group of cancers of the immune system. NHLs can occur at any age, and are often marked by enlarged lymph nodes, fever, and weight loss. There are many different types of NHL, and they can be divided into aggressive (fast-growing) and indolent (slow-growing) types, and are classified as either B-cell or T-cell NHL. B-cell NHLs include Burkitt's lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, precursor B-lymphoblastic lymphoma, and mantle cell lymphoma. T-cell NHLs include mycosis fungoides, anaplastic large cell lymphoma, and precursor T-lymphoblastic lymphoma. Lymphomas related to lymphoproliferative disorders following bone marrow or stem cell transplantation are usually B-cell NHLs. Prognosis and treatment depend on the stage and type of disease.

noni

Morinda citrifolia. A tropical shrub. An extract from the fruit is being studied as a treatment for cancer, and extracts from the fruit, leaves, or roots have been used in some cultures to treat other diseases.

nonlytic

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

nonmalignant

Not cancerous.

nonmalignant hematologic disorder

A disorder of the blood. Some nonmalignant hematologic disorders may lead to leukemia.

nonmelanoma skin cancer

Skin cancer that arises in basal cells or squamous cells but not in melanocytes (pigment-producing cells of the skin).

nonmelanomatous

Having to do with skin cancer that develops in basal cells or squamous cells but not in melanocytes (pigment-producing cells of the skin).

nonmetastatic

Cancer that has not spread from the primary (original) site to other sites in the body.

nonopioid

A drug that is not an opioid. Examples include acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDS), such as aspirin and ibuprofen.

nonpenetrance

The state in which a genetic trait, although present in the appropriate genotype, fails to manifest itself in the phenotype (e.g., a woman with a BRCA1 mutation who lives to be elderly and never develops breast or ovarian cancer).

nonprescription

A medicine that can be bought without a prescription (doctor's order). Examples include analgesics (pain relievers) such as aspirin and acetaminophen. Also called over-the-counter (OTC).

nonrandomized clinical trial

A clinical trial in which the participants are not assigned by chance to different treatment groups. Participants may choose which group they want to be in, or they may be assigned to the groups by the researchers.

nonseminoma (non-sem-ih-NO-ma)

A group of testicular cancers that begin in the germ cells (cells that give rise to sperm). Nonseminomas are identified by the type of cell in which they begin and include embryonal carcinoma, teratoma, choriocarcinoma, and yolk sac carcinoma.

non-small cell lung cancer

A group of lung cancers that includes squamous cell carcinoma, adenocarcinoma, and large cell carcinoma.

nonspecific immune cell

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

nonsteroidal anti-inflammatory drug

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

nonsteroidal aromatase inhibitor

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

nontoxic

Not harmful or destructive.

Novantrone

A drug used to treat advanced prostate cancer that does not respond to hormones, adult acute nonlymphocytic leukemia, and advanced or chronic multiple sclerosis. It is also being studied in the treatment of other cancers. It belongs to the family of drugs called antitumor antibiotics. Also called mitoxantrone.

novobiocin

An antibiotic drug used to treat infection.

NPO

A Latin abbreviation for "nothing by mouth."

NR-LU-10 antigen

A protein found on the surface of some cancers.

NSAID

Nonsteroidal anti-inflammatory drug. A drug that decreases fever, swelling, pain, and redness.

NSC 655649

A substance that is being studied in the treatment of cancer. It is similar to rebeccamycin. It belongs to the families of drugs called antineoplastic antibiotics and topoisomerase I inhibitors. Also called rebeccamycin analog.

nuclear grade

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. Cancers with low nuclear grade grow and spread less quickly than cancers with high nuclear grade.

nuclear magnetic resonance imaging (NOO-klee-er mag-NET-ik REZ-o-nans IM-a-jing)

NMRI. 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. These pictures can show the difference between normal and diseased tissue. NMRI makes better images of organs and soft tissue than other scanning techniques, such as CT or X-ray. NMRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. Also called magnetic resonance imaging (MRI).

nuclear medicine scan

A method of diagnostic imaging that uses very small amounts of radioactive material. The patient is injected with a liquid that contains the radioactive substance, which collects in the part of the body to be imaged. Sophisticated instruments detect the radioactive substance in the body and process that information into an image.

nurse

A health professional trained to care for people who are ill or disabled.

nursing home

A place that gives care to people who have physical or mental disabilities and need help with activities of daily living (such as taking a bath, getting dressed, and going to the bathroom) but do not need to be in the hospital.

nutraceutical

A food or dietary supplement that is believed to provide health benefits.

nutrient

A chemical compound (such as protein, fat, carbohydrate, vitamins, or minerals) that make up foods. These compounds are used by the body to function and grow.

nutrition

The taking in and use of food and other nourishing material by the body. Nutrition is a 3-part process. First, food or drink is consumed. Second, the body breaks down the food or drink into nutrients. Third, the nutrients travel through the bloodstream to different parts of the body where they are used as "fuel" and for many other purposes. To give the body proper nutrition, a person has to eat and drink enough of the foods that contain key nutrients.

nutritionist

A health professional with special training in nutrition who can help with dietary choices. Also called a dietitian.

nystatin

A drug that treats infections caused by fungi.