Medical Glossary


Medical glossary’s can sometimes be more confusing than helpful. We have tried to make ours as pertinent as possible regarding the terminology you, or a loved one, may encounter with a diagnosis/treatment of cancer.

Understandably, we could not cover every word, but if you ever come across a word and/or term that your doctor/physician/oncologist uses that you do not understand, ask them to explain it.


Some tips to navigating cancer terminology –


·        Ask what the word means

·        Write it down

·        Write the explanation down

·        Read back what you have written to make sure you have got it right

·        Keep a journal 


Remember - listen, ask, write and repeat.


It is not uncommon to be overwhelmed with the information being presented, but it is necessary to ensure that you and/or your loved one understand it.





adeno - prefix meaning "gland."

adenocarcinoma - a cancer originating from the epithelium of a glandular organ.

adjuvant therapy - post-surgical therapy to prevent a cancer’s recurrence and destroy any cancer cells that have metastasized; may also include palliative therapy.

amino acid - a peptide; the basic building block of proteins (or polypeptides).

antibody - a protein (immuno-globulin) molecule, produced by the immune system, that recognizes a particular foreign antigen and binds to it; if the antigen is on the surface of a cell, this binding leads to cell aggregation and subsequent destruction. Antibodies attack viruses, bacteria, and other foreign substances in the body.

antigen - a molecule (typically found in the surface of a cell) whose shape triggers the production of antibodies that will bind to it.

antioxidant - a chemical found in some fruits and vegetables that is thought to reduce the damage caused by free radicals.

apoptosis - genetically programmed cell death; the natural mechanism used by the body to eliminate cells that are no longer needed.




benign tumor - a noncancerous tumor.

bone marrow transplantation/BMT - a procedure used in the treatment of cancer in which a patient’s diseased bone marrow is destroyed with radiation or chemotherapy, and then replaced with healthy marrow.

bone marrow transplantation, allogeneic - BMT using bone marrow from a donor.

bone marrow transplantation, autologous - BMT using bone marrow from the patient.

Brachytherapy - a radiation treatment in which tiny radioactive pellets are surgically placed in or near a tumor, giving the tumor a high dose of radiation




cancer - a malignant tumor of potentially unlimited growth that expands locally by invasion and systematically by metastasis.

Carcinogen - a substance that increases the risk of cancer.

Carcinoma - cancer originating from epithelial tissue which covers the body’s surface and lines internal organs and glands; most common type of cancer.

Cell - small membrane-bounded compartment filled with a concentrated aqueous solution of chemicals; the building blocks of all living creatures.

Chemotherapy - the treatment or control of cancer using drugs.

Chromosome - a linear end-to-end arrangement of genes and other DNA, sometimes with associated protein and RNA.

clinical trials - the systematic evaluation of new medical treatments which have shown promise in animal and laboratory tests.





deoxyribonucleic acid/DNA - the chemical found in the nucleus of most cells that is the fundamental substance of which genes are composed; a double chain of linked nucleotides (having deoxyribose as their sugars).

Diabetes - any of various abnormal conditions characterized by the secretion and excretion of excessive amounts of urine.




Enzyme - a protein that functions as a catalyst, to speed up a chemical-specific reaction.

Epidemiology - the study of incidence, distribution and control of disease in a population and the relationship between lifestyle, environment and disease.

Epithelium - the outside layer of cells.




Gene - the fundamental physical and functional unit of heredity that carries information from one generation to the next; a segment of DNA composed of a transcribed region and a regulatory sequence that makes transcription possible; genes code for proteins.

gene mutation - a point mutation that results from changes within the structure of a gene.

gene therapy - techniques that introduce new genetic material into a patient, correcting genetic defects that are causing disease.  

Genome - all the genetic information necessary to build a living creature (i.e., the human genome contains all the information necessary to build a human being).




Hodgkin’s disease - cancer of the lymphatic system; symptoms include enlargement of the lymph nodes, spleen and liver, as well as progressive anemia.

Hormone - a substance secreted by an organ or gland into the bloodstream to be carried to other organs and glands where it has a specific effect; there are two types of hormone: steroid hormones (e.g., estrogen, testosterone) composed of cholesterol are fat soluble and can easily cross the cell membrane; nonsteroid hormones (e.g., insulin) composed of amino acids are water soluble, and cannot cross the cell membrane.




immune system - the animal cells and tissues involved in recognizing and attacking foreign substances within the body.

Immunology - the study of the immune system.

Immunotherapy - therapy for disease through enhancement or stimulation of the immune system.

Interferon - a group of proteins with antiviral and anti-tumor properties that is created by infected cells in response to viruses and foreign nucleic acids; it can also be created synthetically; the three types of inter-feron help immunocompromised patients: alpha, made by leukocytes; beta, made by fibroblasts; and gamma, made by lymphocytes.

invasive cancer - cancer which has spread to surrounding tissue.




Leukemia - cancer of the blood-forming tissues, leukocytes or the cells which give rise to leukocytes.

Leukocytes - white blood cells or corpuscles, including neutrophils, basophils, eosinophils, lymphocytes and monocytes.

localized cancer - cancer which has not spread beyond the origination site.

Lumpectomy - removal of a breast tumor only leaving behind the rest of the breast tissue; the standard procedure for tumors less than one inch in diameter.

lymph glands/nodes - nodules or rounded bodies, varying in size from a pinhead to an olive, found clustered in the neck, armpit, crotch and along the great vessels of the abdomen.

Lymphoma - cancer of the lymphatic system.




Malignant - cancerous.

Mastectomy - the surgical removal of the breast.

melanoma, malignant - the most serious form of skin cancers; originates in the pigment cells of the skin, eye and mucous membranes.

Metastasis - the spread of cancer cells to parts of the body distant from the origination site; only cancerous tumors can metastasize.

molecular genetics - the study of the molecular processes underlying gene structure and function.

monoclonal antibody/MAB - a laboratory-made, highly specific antibody used to detect predetermined proteins or portions of proteins.

Mutagen - an agent that is capable of increasing the mutation rate.  Mutation - 1) the process that produces a gene or a chromosome set differing from the wild-type; 2) the gene or chromosome set that results from such a process.

Myeloma - a cancer of the bone marrow.




non-invasive cancer - the earliest stage of cancer when it is located only in the origination site, before metastasis.




Oncology - the study and treatment of cancer.

Oncoprotein - the protein coded for by an oncogene, capable of causing tumor formation; can be either a mutated form of a normal cellular protein or a normal cellular protein expressed at an inappropriate time.




P53 - tumor suppressor gene.

Pap test - the collection of cervical cells using a cotton swab; the cells are then examined under a microscope to determine if there are cancer cells present.

Pathogen - an organism that causes disease in another organism.

Peptide - an amino acid; the basic building block of polypeptides (or proteins).

Placebo -an inactive substance given to satisfy a patient’s psychological need for medication or used in studies testing the efficacy of a new drug.

Platelets - the cells in the bloodstream responsible for clotting.

polymerase chain reaction/PCR - a technique that amplifies nucleic acid sequences exponentially.

Protein - long linear polymers of amino acids joined head to tail by a peptide bond between the carboxylic acid group of one amino acid and the amino group of the next; proteins determine the shape and structure of the cell and also serve as instruments of molecular recognition.  

Protocol - guidelines to follow in a clinical trial; outlines how a study is to be conducted, who may participate, how to administer treatment and how outcomes are to be recorded.




radiation therapy/radiotherapy - the use of radiation (high energy penetrating rays or subatomic particles) such as X-rays and gamma rays to treat or control disease.

radical mastectomy - the surgical removal of the breast along with the underlying muscle, axillary lymph nodes and fat tissue.

radical prostatectomy - the surgical removal of the prostate and surrounding tissue.

Recurrence - return of a disease after a period without symptoms or signs of the disease.

ribonucleic acid/RNA - a single-stranded nucleic acid similar to DNA, but having ribose sugar rather than deoxyribose sugar, and uracil rather than thymine as the bases.




Sarcoma - cancer arising from connective tissue (bone, cartilage, muscle); also affects liver, lungs, spleen, kidneys and bladder.

secondary tumor - a metastatic tumor, not the original tumor.

squamous cell carcinoma - skin cancer arising from the squamous "scaly" epithelium of the skin.

stem cell - a cell that gives rise to other cells; usually less differentiated than the cells of the tissue.




T cells/T lymphocytes - lymphocytes responsible for the cell-mediated immune response; mature in the thymus gland.

Translocation - detachment of a piece of one chromosome and reattachment to another chromosome during segregation; can cause abnormally long and short chromosomes.

Tumor - an abnormal mass of cells; can be benign or malignant.

tumor suppressor gene - a gene whose loss of function leads to cell transformation and the development of a tumor.