allele - Any of the alternative forms of a gene that are located together on a chromosome. For autosomal chromosomes, each allele will normally have two copies of the same gene, one inherited from the mother and one from the father.

angiogenesis - Growth of new blood vessels.

antibody - A type of protein made by certain white blood cells in response to a foreign substance (antigen). Antibodies bind to the antigen and either destroy the foreign substance directly or make it easier for the body to do so.

bioinformatics - The collection, classification, storage, and analysis of biochemical and biological information using computers especially as applied in molecular genetics and genomics.

biomarker - A substance sometimes found in the blood, other body fluids, or tissues that can be used to assess the presence of cancer.

cohort study - A research study that compares a particular outcome, such as lung cancer, in groups of individuals who are alike in many ways but differ by a certain characteristic - for example, female nurses who smoke compared with those who do not smoke.

enzyme - A protein that speeds up chemical reactions in the body.

epidemiology - The study of the patterns, causes, and control of disease in groups of people.

epithelium - The thin layer of tissue that covers organs, glands, and other structures within the body.

gene expression - The process by which a gene's coded information is converted into the structures present and operating in the cell.

genome - The complete genetic material of an organism.

hyperplasia - An abnormal increase in the number of cells in an organ or tissue.

hypoxia - A condition in which there is a decrease in the oxygen supply to a tissue. In cancer treatment, the level of hypoxia in a tumor may help predict the response of the tumor to the treatment.

immunotherapy - Treatment to stimulate or restore the ability of the immune system to fight infections and other diseases. Also used to lessen side effects that may be caused by some cancer treatments.

lymphochip - A microarray from lymphoma biopsy samples used to analyze DNA differences in large B-cell lymphoma.

magnetic resonance imaging (MRI) - 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.

mass spectroscopy - A method used to identify the chemical make up of a substance by separating the gaseous ions according to their differing mass and charge.

metastasis - The spread of cancer from one part of the body to another. A tumor formed by cells that have spread is called a "metastatic tumor" or a "metastasis." The metastatic tumor contains cells that are like those in the original (primary) tumor. The plural form of metastasis is metastases.

molecular marker - A diagnostic indicator used to determine whether disease may develop.

molecular signature - Characteristic features of the molecular composition of a cell or its surroundings.

molecularly targeted therapy - In cancer treatment, substances that kill cancer cells by targeting key molecules involved in cancer cell growth.

mutation - A permanent change in the genetic material, usually in a single gene.

nanotechnology - Technology development at the atomic, molecular, or macromolecular range of approximately 1-100 nanometers to create and use structures, devices, and systems that have novel properties.

pharmacology - The study of the properties and reactions of drugs, especially with relation to their therapeutic value.

positron emission tomography (PET) scan - A procedure in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the glucose is used. Because cancer cells often use more glucose than normal cells, the pictures can be used to find cancer cells in the body.

precursor cells - Cells that are in a period of rapid division but not yet fully differentiated cancer cells.

prostaglandin - Fatty acids composed of a chain of 20 carbon atoms that perform a variety of hormone-like actions.

protease inhibitor - Drugs that block the action of proteasomes, cellular complexes that break down proteins.

retrospective study - A study that looks backward in time, usually using medical records and interviews with patients who already have or had a disease.

spiral computed tomography (spiral CT) - A scanning technique used to create a three-dimensional image from a series of computer images made by rotating a scanner around the body.

staging - Performing exams and tests to learn the extent of the cancer within the body, especially whether the disease has spread from the original site to other parts of the body. It is important to know the stage of the disease in order to plan the best treatment.

stem cell - A cell from which other types of cells can develop.

T-cells - One type of white blood cell that attacks virus-infected cells, foreign cells, and cancer cells. T cells also produce a number of substances that regulate the immune response.

transcription factor - A protein that binds to DNA and plays a role in the regulation of gene expression by promoting transcription.

translocation - Transfer of part of a chromosome to a different position especially on a nonhomologous chromosome.

tumor suppressor gene - Genes in the body that can suppress of block the development of cancer.

x-ray crystallography - An analytical technique in which X-ray diffraction is used to obtain information about the identity or structure of a crystalline substance.