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Glossary of Myeloma Terms & Definitions

The following guide identifies commonly used myeloma terms and definitions.

Click here to download a PDF version.


Accrual: The process of enrolling patients in a clinical trial (research study), or the number of patients already enrolled in a trial or anticipated to enroll in a trial.

Acute: A sudden onset of symptoms, or disease, or change.

Acute tubular necrosis (ATN): The death of tubular epithelial cells that form the renal tubules of the kidneys. ATN is a form of acute renal failure. Kidney function can be recovered when not all tubular cells are affected.

Adrenal glands: Glands located at the top of the kidneys that are chiefly responsible for releasing sex hormones and cortisol, a hormone that helps human beings respond to stress.

Adrenocortical steroid: Any of the steroidal hormones produced by the adrenal cortex (the outer part of the adrenal gland) or their synthetic (man-made) equivalents. Also known as adrenocorticoids, glucocorticosteroids, or corticosteroids.

Albumin (ALB): Simple water-soluble protein that is found in blood serum. Production is inhibited by interleukin-6 when myeloma is

very active.

Albuminuria: The presence of an excess of serum albumin in the urine.

Alkylating agent: A chemotherapeutic agent such as melphalan or cyclophosphamide. Alkylating refers to the way in which these agents cross-link the DNA of myeloma cells and block cell division.

Allogeneic: See “Transplant.

Amyloid light-chain amyloidosis (AL amyloidosis): A condition in which myeloma light chains cross-link with each other in a beta-pleated fashion and then are deposited in tissues and organs throughout the body, such as the heart, nerves, and kidneys, rather than being excreted through the kidneys. This condition is also known as primary amyloidosis.

Amyloidosis: A general term for a group of diseases characterized by cross-linked light chains. The light chains form rigid fibrils that are insoluble and that are deposited in various organs or tissues. Different types of amyloidoses have different signs and symptoms depending on where and in which organs the amyloid proteins are deposited. 

Analgesic: Any drug that relieves pain. Aspirin and acetaminophen are mild analgesics.

Analog: A chemical compound that is structurally similar to another but differs slightly in composition.

Anemia: A decrease in hemoglobin contained in red blood cells that carry oxygen to the body’s tissues and organs. Anemia is usually defined as hemoglobin below 10 g/dL, with over 13–14 g/dL considered normal, and/or a decrease of ≥ to 2 g/dL from the normal level for an individual.

Anesthesia: Loss of feeling or awareness. Local anesthesia causes loss of feeling in a part of the body. General anesthesia induces loss of sensation with or without loss of consciousness.

Angiogenesis: Blood vessel formation, which usually accompanies the growth of malignant tissue, including myeloma.

Angiogenesis inhibitors: Compounds that reduce new blood vessel formation associated with myeloma (cancer cell) growth. 

Ankylosing spondylitis: A form of chronic inflammation of the spine and the sacroiliac joints.

Anti-emetic agent: A drug that prevents or controls nausea

and vomiting.

Anti-inflammatory: A substance or treatment that reduces inflammation or swelling.

Antibiotics: Drugs used to treat infection.

Antibody: A protein produced by white blood cells called plasma cells to fight infection and disease.

Antifungal agent: A drug used to treat fungal infections.

Antigen: Any foreign substance (such as bacteria, a virus, toxin, or tumor) that causes the immune system to produce natural antibodies.

Antineoplastic agent: A drug that prevents, kills, or blocks the growth and spread of cancer cells.

Apheresis: Sometimes called leukapheresis, apheresis is a pro­cedure in which blood is taken from a patient or donor and the portion of the blood containing plasma, white blood cells, and platelets is separated. Red blood cells are transfused back into the donor. The portion containing white blood cells contains the rare stem cells. 

Appendicular skeleton: The long bones (arms and legs) that are attached to the spine, chest, and pelvis.

Apoptosis: A normal cellular process leading to the death of a cell.

Arm: One of the treatment groups of a randomized trial. The majority of randomized trials have two, but some have more. 

Aspiration: The process of removing fluid or tissue, or both, from a specific area such as the bone marrow.

Asymptomatic myeloma: Myeloma that presents no signs or symptoms of disease (i.e., anemia, renal failure, hypercalcemia, and lytic lesions). Also called smoldering multiple myeloma (SMM) or early-stage myeloma.

Autocrine: Autocrine refers to the process whereby a growth factor is both produced by a cell (such as myeloma) and can also stimulate myeloma cell growth, creating a positive autocrine loop. In a similar fashion, in a paracrine loop, factors produced by the microenvironment surrounding myeloma can stimulate myeloma. Stimulated myeloma cells produce factors which can in turn stimulate microenvironmental cells.

Autologous: See “Transplant.”

Axial skeleton: Spine, pelvis, ribs, and skull. In myeloma, the axial skeleton along with the upper ends of the long bones of the arms and legs are most commonly affected by myeloma.

B-cells (B-lymphocytes): White blood cells that are part of the natural immune system. Some B-cells develop into plasma cells in the bone marrow and are the source of antibodies.

Bacteria: Single-celled microorganisms that can exist either as independent (free-living) organisms or as parasites (dependent on another organism for life). The plural of bacterium.

Basophil: A type of white blood cell. Basophils are a type of granulocyte.

Bence-Jones myeloma: Myeloma char­acterized by the presence of Bence-Jones protein, an abnormal protein in urine made up of free kappa or lambda light chains.

Bence-Jones protein: A myeloma monoclonal protein. The protein is composed of either free kappa or free lambda light chains. Because of their small size, Bence-Jones light chains pass freely into the urine. The amount of Bence-Jones protein in the urine is expressed in terms of grams per 24 hours. Normally, a very small amount of protein (<0.1 g/24 h) can be present in the urine, but this is albumin rather than Bence-Jones protein. The presence of any Bence-Jones protein in the urine is abnormal.

Benign: Not cancerous; does not invade nearby tissue or spread to other parts of the body. MGUS is a benign condition.

Beta-2 microglobulin (also called β2-microglobulin, β2M, or β2M): A small protein found in the blood. High levels occur in patients with active myeloma. Low or normal levels occur in patients with early myeloma and/or inactive disease. Approximately 10% of patients have myeloma that does not produce β2M. At the time of relapse, β2M can increase before there is any change in the myeloma protein level. Factors such as viral infection can sometimes produce elevated serum β2M levels.

Biopsy: The removal of a sample of tissue for microscopic examination to aid in diagnosis.

Bisphosphonate: A type of drug that protects against osteoclast activity (bone breakdown) and binds to the surface of bone where it is being resorbed or destroyed.

Blood cells: Minute structures produced in the bone marrow; they include red blood cells, white blood cells, and platelets.

Blood count: The number of red blood cells, white blood cells, and platelets in a sample of blood.

Blood glucose: The measured blood level of a type of sugar that comes from carbohydrates. It is one of the main sources of energy used by the body.

Blood urea nitrogen (BUN): A measure of the urea level in the blood. Urea is excreted by the kidneys. BUN is a laboratory blood test to assess how well the kidney is functioning. Diseases such as myeloma, which compromise kidney function, frequently lead to increased levels of BUN in the bloodstream.

Bone marrow: The soft, spongy tissue in the center of bones that produces white blood cells, red blood cells, and platelets. This is the tissue within which abnormal plasma cells build up to cause myeloma.

Bone marrow aspiration: The removal, by a needle, of a sample of fluid and cells from the bone marrow for examination under a microscope.

Bone marrow biopsy: The removal, by a needle, of a sample of tissue from the bone. The cells are checked to see whether they are cancerous. If cancerous plasma cells are found, the pathologist estimates how much of the bone marrow is affected. Bone marrow biopsy is usually done at the same time as bone marrow aspiration.

Bone marrow transplant: See “Transplant.”

Bone remodeling: The normal coordination (coupling) between osteoclast cells (which resorb or destroy bone) and osteoblast cells (which create new bone matrix) to maintain a balanced state of bone production and destruction.

C-reactive protein (CRP): A protein made in the liver that rises when there is inflammation throughout the body.

Calcium: A mineral found mainly in the hard part of bone matrix or hydroxyapatite. If produced or released in excess, it can build up in the bloodstream. See “Hypercalcemia.”

Cancer: A term for diseases in which malignant cells divide without control. Cancer cells can invade nearby tissues and spread through the bloodstream and lymphatic system to other parts of the body.

Carcinogen: Any substance or agent that produces or stimulates cancer growth.

Catheter: A tube that is placed in a blood vessel to provide a pathway for drugs or nutrients. A central venous catheter (CVC) is special tubing that is surgically inserted into a large vein near the heart and exits from the chest or abdomen. The catheter allows medications, fluids, or blood products to be given; and blood samples to be taken.

CD34+: The laboratory marker used to single out and quantify the number of stem cells in your blood stream. A certain minimum number of CD34+ stem cells are required to safely support a transplant procedure.

Cell: The basic unit of any living organism. Millions of microscopic cells comprise each organ and tissue in the body.

Cell differentiation: The process during which young, immature (unspecialized) cells take on individual characteristics and reach their mature (specialized) form and function.

Cell proliferation: An increase in the number of cells as a result of cell growth and cell division.

Chemotherapeutic agents: Any drugs used to kill cancer cells. “Combination chemotherapy” uses more than one drug in a cancer treatment regimen.

Chromosome: A strand of DNA and proteins in the nucleus of a cell. Chromosomes carry genes and function in the transmission of genetic information. Normally, human cells contain 46 chromosomes.

Chronic: Persisting over a long period of time.

Clinical: Involving direct observation or examination of a patient.

Clinical trial: A research study of new treatment that involves patients. Each study is designed to find better ways to prevent, detect, diagnose, or treat cancer and to answer scientific questions.

• Control group – The arm of a randomized clinical trial that gets the standard treatment or placebo (no treatment).

• End point – The goal of the trial; what a clinical trial is trying to measure or find out. Typical end points include measurements of toxicity, response rate, and survival.

• Experimental group – The arm of a randomized trial that gets the new treatment.

• Phase I trial – A trial designed to determine the maximum-tolerated dose (MTD) of a new drug or a new combination of drugs. It is usually the first human testing of a new treatment, although in phase I trials of combination therapies, the individual elements may already have been well tested. Patients in phase I trials generally have advanced cancer that is refractory to all standard treatment. In a typical phase I trial, successive groups (“cohorts”) of 3 to 6 patients are given the treatment. All patients in a cohort get the same dose. The first cohort typically gets a very low dose, and the dose is raised in each subsequent cohort until a set number of patients experience dose-limiting toxicity (DLT). The dose level used for the previous cohort is then taken to be the MTD. This dose is then used in a phase II trial.

• Phase II trial – A trial designed to determine the response rate of a new therapy that has already been tested in phase I trials. Typically, 14 to 50 patients with one type of cancer are treated to see how many have a response. Patients are usually required to have advanced cancer that is refractory to any standard treatment, and in addition, they must have measurable disease. If results from a phase II trial are promising enough, the treatment may then be tested in a phase III trial. If the results are obviously much better than the standard treatment, then it may not be necessary to do a phase III trial, and the treatment may become standard-based on phase II trial results.

• Phase III trial – A trial designed to compare two or more treatments for a given type and stage of cancer. The end point of a phase III trial is usually survival or disease-free survival. Phase III trials are usually randomized, so patients don’t choose which treatment they receive. A typical phase III trial has 50 to thousands of patients. Some phase III trials compare a new treatment that has had good results in phase II trials with an older, well known, standard treatment. Other phase III trials compare treatments that are already in common use. Some treatments in phase III trials may be available outside the clinical trial setting.

• Randomized clinical trial – A research study in which subjects are randomly assigned to receive a particular treatment or not.

Colony-stimulating factor (CSF): Pro­teins that stimulate the development and growth of blood cells. Neupogen® (filgrastim), Neulasta® (pegfilgrastim)‎, and Leukine® (sargramostim) are colony-stimulating factors that are used to mobilize stem cells from the bone marrow into the blood­stream prior to apheresis. These may also be used after the transplant to hasten blood count recovery.

Complete response: When a cancer responds to such an extent that it is undetectable. For myeloma, a complete response means that the myeloma protein can no longer be detected in the blood and/or urine and that the bone marrow shows no evidence of myeloma.

Computerized axial tomography (CAT or CT) scan: A test using computerized x-rays to create three-dimensional images of organs and structures inside the body, used to detect small areas of bone damage or soft tissue involvement.

Conditioning: A treatment regimen given to a patient to destroy cancer cells prior to stem cell transplant. The most common conditioning regimen given to myeloma patients is 200mg of melphalan per square meter of body mass.

Congestive heart failure: A condition that occurs when the heart’s pumping function is weakened, causing a cascade of events that result in the body retaining fluid and salt. If fluid builds up in the arms, legs, feet, ankles, lungs, or other organs, the body becomes congested.

Corticosteroid:  A group of natural and synthetic analogues of the hormones secreted by the pituitary gland. These include the glucocorticoids used in the treatment of myeloma such as dexamethasone, prednisone, and methylprednisolone. Glucocorticoids have multiple effects, and are used for a large number of conditions.

Creatinine: A small chemical compound normally excreted by the kidneys into the urine. If the kidneys are damaged, the serum level of creatinine builds up, resulting in an elevated serum creatinine. The serum creatinine test is used to measure kidney function.

Cyst: An accumulation of fluid or semi-solid material within a sac. A cyst can occur in any organ or tissue.

Cytokines: Proteins secreted by cells which can stimulate or inhibit growth/activity in other cells. Cytokines are produced locally (i.e., in the bone marrow) and circulate in the bloodstream. They are normally released in response to infection.

Cytoplasm: The jellylike material that makes up much of a human cell inside the cell membrane, and surrounds the nucleus.

Deep vein thrombosis (DVT): A condition that occurs when a blood clot (thrombus) forms in one or more of the deep veins in the body, usually in the legs. Deep vein thrombosis can cause leg pain or swelling, but may occur without any symptoms.

Deoxyribonucleic acid (DNA): The substance of heredity; a large molecule that carries the genetic information that cells need to replicate and to produce all components of the body.

Dexamethasone: A powerful corticosteroid given alone or

with other drugs.

Diagnosis: The process of identifying a disease by its signs and symptoms and test results.

Dialysis: When a patient’s kidneys are unable to filter blood, dialysis is the process whereby the blood is cleaned by passing it through a dialysis machine.

Disease-free survival: The length of time the patient survives without any detectable cancer.

Disease stabilization: When a tumor stops growing and remains the same size.

Dose-limiting toxicity (DLT): Side effects severe enough to prevent giving more of the treatment.

Double blind: Aspect of a randomized trial in which neither the participant nor the investigator knows the aim of the trial to which the patient is assigned. The purpose is to eliminate any bias in the reporting of results. 

Drug resistance: The result of cells’ ability to resist the effects of a specific drug.

Dual-energy x-ray absorptiometry (DXA, previously DEXA) study: Used to measure the density of bone.

Eastern Cooperative Oncology Group (ECOG) status: See “Performance Status.”

Edema: Swelling; an abnormal accumulation of fluid in part of the body.

Efficacy: The power to produce an effect; in cancer research ‘efficacy’ refers to whether the treatment is effective.

Electrolytes: Minerals in your blood and other body fluids that carry an electric charge. They affect the amount of water in your body, the acidity of your blood (pH), your muscle function, and other important processes.

Electrophoresis: A laboratory test in which a patient’s serum (blood) or urine molecules are subjected to separation according to their size and electrical charge. For myeloma patients, electrophoresis of the blood or urine allows both the calculation of the amount of myeloma protein (M?protein) as well as the identification of the specific M-spike characteristic for each patient. Electrophoresis is used as a tool both for diagnosis and for monitoring.

Engraftment: The process by which stem cells in the transplanted bone marrow or peripheral blood migrate to the patient’s bone marrow and begin to grow and produce new white blood cells, red blood cells, and platelets. 

Enzyme: A substance that increases the rate at which chemical changes take place in the body.

Erythrocytes: Red blood cells (RBCs). RBCs carry oxygen to body cells and carbon dioxide away from body cells.

Erythropoiesis: The formation of new red blood cells.

Erythropoietin: A hormone produced by the kidneys. Myeloma patients with damaged kidneys don’t produce enough erythropoietin and can become anemic. Injections with synthetic erythropoietin can be helpful. Blood transfusion is another alternative treatment for anemia, especially in an emergency. Synthetic erythropoietin can be used as a supportive therapy during anti-myeloma treatment to avoid anemia.

Esophagitis: Inflammation of the esopha­gus, which is the tube that transports food from the mouth to the stomach.

Extramedullary plasmacytoma: A tumor made up of monoclonal plasma cells that is found in soft tissue outside of the bone marrow and separate from bone.

Extravasation: Passage or escape of a drug or substance such as bone cement into surrounding tissue.

Facet joint: The connection between the bones of the spine.

Fluorescence in situ hybridization (FISH): A procedure that allows researchers to locate the positions of specific DNA sequences on chromosomes.

Flow cytometry: A technology used in cell counting, cell sorting, and biomarker detection by suspending cells in a stream of fluid and passing them through a laser. 

Focal bone lesion: A tumor or fracture seen on an imaging study such as an x-ray, CT, or MRI.

Free light chain: A portion of the monoclonal protein that is of low molecular weight. It may be bound to a heavy chain or it may be unbound, or free. Free light chains can be measured in a sensitive assay called the Freelite® test.

Gastrointestinal side effects: Side effects of medication that affect the digestive tract, such as nausea, vomiting, diarrhea, and constipation.

Gene: A specific sequence of DNA coding for a particular protein.

Gene therapy: Treatment that alters the activity of genes. This usually implies adding or removing a gene or genes.

Generic drug name: A generic drug name refers to the chemical makeup of a drug rather than to its brand name. A generic name is given to a drug before it is approved and given a brand name.  After a drug goes off patent, other manufacturers may make generic versions of the drug. For example: ibuprofen is the generic name for such drugs brand-named Advil® and Motrin®.

Genetic: Inherited; having to do with information that is passed from parents to children through DNA in the genes.

Glaucoma: A disease associated with the build-up of pressure inside the eye that, if untreated, can result in vision loss and blindness.

Graft-versus-host disease (GVHD): A reaction of donated bone marrow cells against the recipient’s own tissue.

Granulocyte: A type of white blood cell that kills bacteria. Neutrophils, eosinophils, and basophils are all types of granulocytes.

Growth factors: Drugs that stimulate blood stem cells both to grow and to be released into the bloodstream.

Hematocrit (Hct): The percentage of red blood cells in the blood. A low hematocrit measurement indicates anemia.

Hematologic: Originating in the blood, or disseminated by the circulation or through the bloodstream.

Hematologic malignancy: A cancer of the bone marrow or blood cells.

Hematologist: A doctor who specializes in the problems of blood and bone marrow.

Hemoglobin: A protein in red blood cells that carries oxygen.

Herpes simplex: A common virus, it causes sores often seen around the mouth, commonly called cold sores.

Herpes zoster infection: A viral infection that frequently affects nerves. This condition is also called shingles.

Hormones: Chemicals produced by various glands that regulate the actions of certain cells or organs around the body.

Human leukocyte antigen (HLA) test: A blood test used to match a blood or bone marrow donor to a recipient for transfusion or transplant.

Hydroxyapatite: A compound that helps form bones and gives them rigidity and strength.

Hypercalcemia: A higher than normal level of calcium in the blood. In myeloma patients, it usually results from bone breakdown with release of calcium from the bone into the bloodstream. This condition can cause a number of symptoms, including loss of appetite, nausea, thirst, fatigue, muscle weakness, restlessness, and confusion. See “Calcium.”

Hypersensitivity reaction: Undesirable reactions, sometimes in response to a medication, produced by the normal immune system, including allergies and autoimmunity. These reactions may be damaging, uncomfortable, or fatal.

Hypertension: A chronic medical condition in which the blood pressure in the arteries is elevated. Also known as high blood pressure.

Hyposecretory: Low- or non-secreting disease.

IgG, IgA: The two most common types of myeloma. The G and the A refer to the type of protein produced by the myeloma cells. The myeloma protein, which is an immunoglobulin, consists of two heavy chains, (for example, of a G type) combined with two light chains, which are either kappa or lambda. Therefore, the two most common subtypes of myeloma have identical heavy chains (i.e. IgG kappa and IgG lambda). The terms “heavy” and “light” refer to the size or molecular weight of the protein, with the heavy chains being larger than the light chains.

IgD, IgE: Two types of myeloma that occur less frequently.

See “IgG, IgA.”

IgM: Usually associated with Waldenström’s macroglobulemia. In rare cases, IgM can be a type of myeloma.

Immune system: The complex group of organs and cells that produces antibodies, cellular responses to defend the body against foreign substances such as bacteria, viruses, toxins, and cancers.

Immunoassay: Test used in the study of biological systems by tracking differ­ent proteins, hormones, and antibodies. Immunoassays rely on the inherent abil­ity of an antibody to bind to the spe­cific structure of a molecule. Because antibodies are developed to the spe­cific three-dimensional structure of an antigen, they are highly specific and will bind only to that structure. ELISA (enzyme-linked immunosorbent assay) is a commonly used test to detect anti­bodies in the blood.

Immunodeficiency: A lowering of the body’s ability to fight off infection and disease.

Immunofixation electrophoresis (IFE): An immunologic test of the serum or urine used to identify proteins. For myeloma patients, it enables the doctor to identify the M-protein type (IgG, IgA, kappa, or lambda). The most sensitive routine immunostaining technique, it identifies the exact heavy- and light-chain type of M-protein.

Immunofluorescence: This test uses the specificity of antibodies to their antigen to target fluorescent dyes to specific targets within a cell, and there­fore allows visualization of the distribu­tion of the target molecule through the sample. Immunofluorescence makes use of fluorophores to visualize the location of antibodies. A fluorophore is a fluorescent chemical compound that can re-emit light upon light excita­tion. Fluorophores are used as probes or indicators.

Immunoglobulin (Ig): A protein produced by plasma cells; an essential part of the body’s immune system. Immunoglobulins attach to foreign substances (antigens) and assist in destroying them. The classes of immunoglobulins are IgG, IgA, IgD, IgE, and IgM. The non-medical word for immunoglobulin is “antibody.”

Immunohistochemistry (IHC): Immu­nohistochemistry refers to the process of detecting antigens (e.g., proteins) in cells of a tissue section by exploit­ing the principle of antibodies binding specifically to antigens in biological tissues. Immunohistochemical stain­ing is widely used in the diagnosis of abnormal cells such as those found in cancerous tumors.

Immunomodulatory drug (IMiD): An agent that affects, enhances, or suppresses the immune system.

Immunosuppression: Weakening of the immune system that causes a lowered ability to fight infection and disease. Immunosuppression may be deliberate, such as in preparation for bone marrow transplantation to prevent rejection by the host of the donor tissue, or incidental, such as often results from chemotherapy for the treatment of cancer.

Immunotherapy: Treatment that enhances the body’s natural defenses to fight cancer. Also called biological therapy.

Incidence: The number of new cases of a disease diagnosed each year.

Induction therapy: The initial treatment used in an effort to achieve remission in a newly diagnosed myeloma patient.

Inflammatory: Pertaining to a protective response of the body against injury or disease.

Informed consent: The process requiring a doctor to give a patient enough information about a proposed procedure for the patient to make an informed decision about whether or not to undergo the procedure or planned strategy. The doctor must, in addition to explaining all procedures, address the issues of risks, benefits, alternatives, and potential costs.

Infusion: Delivering fluids or medications into the bloodstream over a period of time.

Infusion pump: A device that delivers measured amounts of fluids or medications into the bloodstream over a period of time.

Infusion reaction: An allergic or cytokine-related response to an intravenously administered cancer treatment.

Inhibit: To stop something or hold it in check.

Injection: Introducing a medication into the body with the use of a syringe and needle.

Interferon: A naturally produced hormone (cytokine) released by the body in response to infection or disease that stimulates the growth of certain disease-fighting blood cells in the immune system. Interferon can be artificially produced by genetic engineering techniques and used as a form of immunotherapy, primarily in the maintenance (plateau) phase to block any regrowth of myeloma and thus delay or prevent relapse.

Interleukin: A naturally produced chemical released by the body, or a substance used in biological therapy. Interleukins stimulate the growth and activities of certain kinds of white blood cells. Interleukin-2 (IL-2) is a type of biological response modifier that stimulates the growth of certain blood cells in the immune system that can fight some types of cancer. Interleukin-6 (IL-6) is a cytokine that is a potent stimulus to osteoclast and plasma cell activities.

Interventional radiology: The branch of radiology concerned with providing diagnosis and treatment of disease by a variety of procedures performed through the skin under the guidance of radiologic imaging.

Kyphoplasty: The injection of liquid cement into damaged bone using a bal­loon technique. This procedure may pro­vide acute pain relief and improvement in structural integrity of collapsed vertebrae or other damaged bones.

Kyphosis: An exaggeration of the normal curve of the spine, sometimes referred to as a “hunchback” or “dowager’s hump.”

Lactate dehydrogenase (LDH): An energy-producing enzyme that is present in almost all of the tissues in the body. LDH levels in the bloodstream rise in response to cell damage. LDH may be used to monitor myeloma activity.

Lesion: An area of abnormal tissue. A lump or abscess that may be caused by injury or disease, such as cancer. In myeloma, “lesion” can refer to a plasmacytoma or a hole in the bone.

Leukocytes: Cells that help the body fight infections and other diseases. Also called white blood cells (WBCs).

Leukopenia: A low number of white blood cells.

Lumbar spine: The portion of the spine comprising the lumbar vertebrae. The vertebrae are divided into sections: cervical (neck, 7 vertebrae), thoracic (chest, 12 verte­brae), and lumbar (lower back, 5 verte­brae). Below the lumbar spine are the sacrum and coccyx, both made up of a series of fused vertebrae.

Lupus: Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disorder that can affect the skin, joints, kidneys, and other organs.

Lymphocytes: B-cells, T-cells, and NK cells, which together constitute 30% of white blood cells. B-lymphocytes and T-lymphocytes are responsible for the adaptive immune response, which enables immune system cells to attach to specific antigens on the cell surfaces of infectious organisms, tumors, and other foreign substances.

Lytic (lysis): Dissolution or destruction of cells or tissues.

Lytic lesions: The damaged area of a bone that shows up as a dark spot on an x-ray when at least 30% of the healthy bone in any one area is eaten away. Lytic lesions look like holes in the bone and are evidence that the bone is being weakened.

M-proteins (M-spike): Antibodies or parts of antibodies found in unusually large amounts in the blood or urine of multiple myeloma patients. M-spike refers to the sharp pattern that occurs on protein electrophoresis when an M-protein is present. Synonymous with monoclonal protein and myeloma protein. See “Monoclonal.”

Magnetic resonance imaging (MRI): A diagnostic imaging test that uses magnetic fields and radio waves, not ionizing radiation, to produce detailed two- or three-dimensional images of organs and structures inside the body. MRI gives very fine resolution of soft tissues, especially encroachments on the spinal cord, but is less accurate for bone lesions.

Maintenance therapy: Drugs given to patients in remission to delay or prevent a relapse.

Malignant: Cancerous; capable of invading nearby tissue and spreading to other parts of the body.

Matched unrelated donor (MUD) transplant: See “Transplant.”

Maximum-tolerated dose (MTD): The highest dose of a treatment that most people can safely withstand.

Median:  The middle number in a series of numbers. Thus, median progression-free survival means that half the patients had remissions that were shorter than the median PFS, and half the patients had remissions that were longer than the median PFS. 

Melanoma: A cancer of the pigment-forming cells of the skin or the retina of the eye. Not associated with myeloma despite the similar-sounding name.

Metastasize: To spread from one part of the body to another. When cancer cells metastasize and form secondary tumors, the cells in the metastatic tumor are like those in the original (primary) tumor. This term is commonly used to describe a disease process in solid tumors

(e.g., breast, prostate) and not in myeloma, which is a blood-related cancer.

Minimal residual disease (MRD): The presence of residual tumor cells after treatment has been completed and complete remission (CR) has been attained. Even patients who have attained a stringent complete response (sCR) may have MRD. Very sensitive new testing methods are now able to detect 1 myeloma cell among 1,000,000 sampled cells in blood or bone marrow.

Molecule: The smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms.

Monoclonal: A clone or duplicate of a single cell. Myeloma develops from a single malignant plasma cell (monoclone). The type of myeloma protein produced is also monoclonal; a single form rather than many forms (polyclonal). The important practical aspect of a monoclonal protein is that it shows up as a sharp spike (M-spike) in the serum electrophoresis test.

Monoclonal antibodies: Artificially manufactured antibodies specifically designed to find and bind to cancer cells for diagnostic or treatment purposes. They can be used alone, or they can be used to deliver drugs, toxins, or radioactive material directly to tumor cells.

Monoclonal gammopathy of undeter­mined significance (MGUS): A category of plasma cell disorder characterized by compara­tively low levels of monoclonal protein in the blood and/or urine. Bone marrow plasma cell levels are low (<5%). Myeloma-related symptoms (i.e., anemia, renal failure, hypercalcemia, and lytic lesions) are absent.

Monoclonal protein (M-protein): An abnormal protein produced by myeloma cells that accumulates in and damages bone and bone marrow. A high level of M-protein indicates that myeloma cells are present in large numbers.

Monocyte: A type of white blood cell found in the circulation. Also called a macrophage when present in tissues.

Multi-drug resistance (MDR): A resistance to standard treatment, typically associated with resistance to Adriamycin® (doxorubicin) and vincristine, both chemotherapy drugs. The resistance is caused by a buildup of P-glycoprotein in the outer cell membrane of the myeloma cells. This results in drugs being kicked back out of the myeloma cell instead of building up and eventually killing that cell.

Multiple myeloma: A cancer arising from the plasma cells in the bone marrow. The cancerous plasma cells are called myeloma cells. 

Myeloablation: The killing of bone marrow by radiation or chemotherapy. This term usually refers to the complete or near-com­plete destruction of the bone marrow.

Myelodysplastic syndrome (MDS): A condition in which the bone marrow does not function normally and does not produce enough blood cells. This condition can occasionally progress and become acute leukemia.

Myeloid: Referring to myelocytes, a type of white blood cell. Also called myelogenous. Myeloma is a non-myeloid cancer.

Myelosuppression: A decrease in the production of red blood cells, platelets, and some white blood cells by the bone marrow.

Neoplasia: Abnormal new growth of cells.

Neoplasm: Abnormal new growth of tissue or cells creating a tumor.

Nephrotic syndrome: A group of dis­eases characterized by excretion of large amounts of protein (mostly albumin) into the urine. Because of this, patients frequently develop edema.

Nephrotoxicity: The quality of being toxic or destructive to kidney cells.

Neurosurgeon: A doctor who performs surgery on any part of the nervous system, including the back and the spinal cord.

Neutropenia: A reduced level of neutrophils.

Neutrophil: A type of white blood cell necessary to combat bacterial infection.

Nonsteroidal anti-inflammatory drug (NSAID): A drug used to reduce fever, swelling, pain, and redness.

Nucleus: The nucleus of the cell in advanced organisms is the control center of the cell.  It serves two functions: it stores all the genetic material (DNA) of the cell, and it coordinates the cell's activities, which include growth, intermediary metabolism, protein synthesis, and reproduction (cell division).

Oncogene: A gene or DNA sequence that normally directs cell growth, but which can also promote or allow the uncontrolled growth of cancer if damaged (mutated) by environmental exposure to carcinogens, or if damaged or missing because of an inherited defect. A gene that has the potential to cause a normal cell to become cancerous.

Oncologist: A doctor who specializes in treating cancer. Some oncologists specialize in a particular type of cancer.

Orthopedic surgeon: Orthopedic sur­geons use both surgical and nonsurgical means to treat musculoskeletal trauma, sports injuries, degenerative diseases, infections, tumors, and congenital disorders.

Osteoblast: A bone cell that is asso­ciated with production of bone tissue. Osteoblasts produce osteoid, which becomes mineralized with calcium to form new hard bone.

Osteoclast: A cell found in bone and bone marrow at the junction between the bone marrow and the bone. It is responsible for breaking down or remodeling old bone tissue. In myeloma, the osteoclasts are overstimulated, while osteoblast activity is blocked. The combination of accelerated bone resorption and blocked new bone formation results in lytic lesions.

Osteoid: The protein produced by osteoblasts which becomes mineralized with calcium to form hard bones.

Osteonecrosis of the jaw (ONJ): A jaw problem observed in a small percentage of patients taking bisphosphonates. The condition produces pain, swelling, and bone damage around the tooth sockets in the jaws. Bone necrosis, or loss of bone, occurs and can lead to loose teeth, sharp edges of exposed bone, bone spurs, and the breaking loose of small bone spicules or dead bone. A case definition is ≥3 months with non-healing exposed bone. Symptoms may not be obvious at first, or may include pain, swelling, numbness or a “heavy jaw” feeling, or loosening of a tooth.

Osteoporosis: A progressive bone disease that is characterized by a decrease in bone mass and density, leading to an increased risk of fracture. Diffuse involvement of bones with myeloma produces what looks like osteoporosis on x-ray and bone density measurement.

Overall response rate (ORR): The percentage of patients in a clinical trial whose monoclonal protein dropped by at least 50% in response to treatment.

Overall survival (OS): For a group of individuals suffering from a cancer, this term denotes the chances of staying alive. It denotes the median number of individuals in the group who are likely to be alive after a particular duration of time. At a basic level, OS is representative of cure rates. OS is often used as a measure of treatment efficacy in clinical trials.

Palliative treatment: A treatment designed to improve the quality of life by relieving pain and symptoms of disease but not intended to alter its course.

Partial response: When myeloma is reduced by 50% with treatment. 

Pathogen: An infectious agent such as a virus, bacterium, prion, fungus, viroid, or parasite that causes disease in its host.

Pathological fracture: A break in a bone usually caused by cancer or some disease condition. Occurs in myeloma-weakened bones, which can’t bear normal weight or stress.

Pathology: The study of disease by the examination of tissues and body fluids under the microscope. A doctor who specializes in pathology is called a pathologist.

Performance status: A measure of the level of activity of which a patient is capable. By implication, a measure of the severity of disease. Also called ECOG status.

Peripheral blood stem cell transplant: See “Transplant.”

Peripheral neuropathy (PN): Numbness, tingling, and/or pain in the hands, feet, legs, and/or arms.

Pharmacodynamics: The study of the action or effects of drugs on human cells. 

Pharmacogenetics or pharmacogenomics: Interchangeable terms that refer to the study of specific changes in genes that result in various responses to treatments. 

Pharmacokinetics: The study of the processes by which a drug is absorbed, distributed, metabolized, and eliminated by the body. 

Phlebitis: Inflammation of a vein.

Placebo:  An inert (inactive) substance often used in clinical trials for comparison with an experimental drug. No clinical trial for cancer patients in the United States can ethically or legally randomize patients to receive a placebo alone when they require treatment. In the placebo arm of a cancer treatment trial, patients receive treatment with approved therapy plus a placebo.

Plasma: The liquid part of the blood in which red blood cells, white blood cells, and platelets are suspended.

Plasma cells: Special white blood cells that produce antibodies (immunoglobulins). Myeloma is a cancer of the plasma cells. Malignant plasma cells are called myeloma cells. In myeloma, malignant plasma cells produce large amounts of abnormal antibodies that lack the capability to fight infection. These abnormal antibodies are the monoclonal protein, or M-protein, that functions as a tumor marker for myeloma. Plasma cells also produce other chemicals that can cause organ and tissue damage (i.e., anemia, kidney damage, and nerve damage).

Plasmacytoma: See "Extramedullary plasmacytoma" and "Solitary plasmacytoma of the bone (SPB)."

Plasmapheresis: The process of removing certain proteins from the blood. Plasmapheresis can be used to remove high levels of monoclonal myeloma protein from the blood of myeloma patients.

Platelets: One of the three major blood elements, others being the red blood cells and white blood cells. Platelets plug up breaks in the blood vessel walls and release substances that stimulate blood clot formation. Platelets are the major defense against bleeding. Also

called thrombocytes.

Positron emission tomography (PET): A diagnostic test that uses a sophisticated camera and computer to produce images of the body. PET scans show the difference between healthy and abnormally functioning tissues based upon the uptake of radiolabeled sugar by active cancer cells. 

Port (implanted): A catheter connected to a quarter-sized disc that is surgically placed just below the skin in the chest or abdomen. The catheter is inserted into a large vein or artery directly into the bloodstream. Fluids, drugs, or blood products can be infused, and blood can be drawn through a needle that is inserted into the disc.

Precancerous: A term used to describe a condition that may or may not become cancer.

Prognosis: The projected outcome or course of a disease. The chance of recovery. It can also mean the life expectancy.

Progression-free survival (PFS): The improved survival of a patient that can be directly attributed to the treatment given for the myeloma. The time period during which the patient survives, and the myeloma does not regrow or relapse. See “Progressive disease.”

Progressive disease: Myeloma that is becoming worse or relapsing, as documented by tests. Defined as a ≥ 25% increase in the myeloma protein level and/or new evidence of disease. 

Proteasome: A joined group (or complex) of enzymes that destroy damaged or unwanted proteins and undamaged proteins that require degradation in the cell. This turnover or “recycling” of proteins is important to maintain balance within the cell and helps to regulate several functions including cell growth.

Proteasome inhibitor: Any drug that interferes with the normal function of the proteasome, an enzyme complex responsible for breaking down and recycling unwanted proteins in both normal cells and cancer cells.

Proteins: Substances composed of amino acids. Proteins are an essential part of all living organisms, especially as structural components of body tissues such as muscle, hair, collagen, and so forth, as well as enzymes and antibodies.

Protein electrophoresis: A laboratory test in which a patient’s serum (blood) or urine proteins are subjected to separation according to their size and electrical charge. Electrophoresis allows for the calculation of the amount of monoclonal protein and is used both for diagnosis and for monitoring.

Protocol: A detailed plan of treatment including the dose and schedule of any drugs used.

Pulmonary embolism (PE): A condition that occurs when a blood clot in the vein (deep vein thrombosis, or DVT) breaks loose, travels through the bloodstream, and lodges in a lung, blocking blood flow.

Radiation therapy: Treatment with x-rays, gamma rays, or electrons to damage or kill malignant cells. The radiation may come from outside the body (external radiation) or from radioactive materials placed directly in the tumor (implant radiation).

Radiologist: A doctor who specializes in creating and interpreting images of areas inside the body. The images are produced with x-rays, sound waves, magnetic fields, or other types of energy.

Recurrence: The reappearance of a disease after a period of remission.

Red blood cells (erythrocytes): Cells in the blood that contain hemoglobin and deliver oxygen to and take carbon dioxide from all parts of the body. Red cell production is stimulated by a hormone (erythropoietin) produced by the kidneys. Myeloma patients with damaged kidneys don’t produce enough erythropoietin and can become anemic. Myeloma patients can also become anemic because of myeloma cells’ effect on the ability of the bone marrow to make new red blood cells.

Refractory: Disease that is no longer responsive to standard treatments.

Regression: The shrinkage in size of a cancer or tumor.

Relapse: The reappearance of signs and symptoms of a disease after a period of improvement.

Relapsed or refractory: Patients with relapsed disease have been treated and then have developed signs and symptoms of myeloma at least 60 days after treatment has ended. Patients with refractory myeloma have had progressive disease either during treatment or within 60 days following treatment. Most clinical trials for advanced disease are for patients with relapsed and/or refractory myeloma. 

Remission or response: Complete or partial disappearance of the signs and symptoms of cancer. Remission and response are interchangeable terms.

Complete remission (CR) – CR is negative immunofixation on serum and urine, and disappearance of any soft tissue plasmacytomas, and less than or equal to 5% plasma cells in bone marrow. CR is not the same as a cure.

Stringent complete response (sCR) – sCR is CR (as defined below) plus normal FLC ratio and absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence.

Partial remission (PR) – PR is a level of response in which there is at least a 50% reduction in M-protein, and reduction in 24-hour urinary M-protein by at least 90% (or to less than 200mg/24hrs).

Very good partial remission (VGPR) – VGPR is less than CR. VGPS is serum M-protein and urine M-protein detectable by immunofixation but not on electrophoresis, or 90% or greater reduction in serum M-protein, plus urine M-protein <100mg per 24 hours.

Research Study: See “Clinical Trial.”

Ribonucleic acid (RNA): Any of various nucleic acids that are associated with the control of cellular chemical activities. RNA is one of the two nucleic acids found in all cells – the other is DNA (deoxyribonucleic acid). RNA transfers genetic information from DNA to proteins produced by the cell.


Sacrum: A large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx (tailbone).

Scleroderma: A connective tissue disorder characterized by tightening of the skin of the arms, face, or hands; puffy hands and feet; and joint stiffness. It can affect one part of the body or the entire body.

Serum: The colorless, liquid part of blood in which the blood cells are suspended.

Serum osteocalcin: A protein produced and secreted by osteoblasts when they are making osteoid. A low level reflects active myeloma. A higher than normal level reflects more stable myeloma.

Serum sickness: A hypersensitivity reaction caused by the administration of a foreign serum; it causes fever, swelling, skin rash, and enlargement of the lymph nodes.

Shingles: See “Herpes zoster infection.”

Side effects: Unwanted effects caused by a drug.

Skeletal-related event (SRE): Bone damage or fracture.

Skeletal survey (metastatic survey): A series of plain x-rays of the skull, spine, ribs, pelvis, and long bones to look for lytic lesions

and/or osteoporosis.

Solitary plasmacytoma of bone (SPB): A discreet, single mass of monoclonal plasma cells in a bone. The diagnosis of SBP requires a solitary bone lesion, a biopsy of which shows infiltration by plasma cells; negative imaging results for other bone lesions; absence of clonal plasma cells in a random sample of bone marrow; and no evidence of anemia, hypercalcemia, or renal involvement suggesting systemic myeloma.

Spinal cord: A long, thin, tubular bundle of nervous tissue and support cells that extends from the brain. The brain and spinal cord together make up the central nervous system. The spinal cord begins at the occipital bone and extends down to the space between the first and second lumbar vertebrae.

Stable disease: This describes patients who have some response to treatment but with <25% improvement or progression in protein level. With slow-moving myeloma, stabilization can last for many years.

Stage: The extent of a cancer in the body.

Staging: Doing exams and tests to learn the extent of the cancer in the body.

Stem cells (hematopoietic stem cells): The immature cells from which all blood cells develop. Normal stem cells give rise to normal blood components, including red cells, white cells, and platelets. Stem cells are normally located in the bone marrow and can be harvested for transplant.

Steroid: A type of hormone. Steroids are often given to myeloma patients along with one or more anticancer drugs and typically enhance the anti-myeloma treatment benefit.

Supportive care: Treatment given to prevent, control, or relieve complications and side effects and to improve the patient’s comfort and quality of life.

Syngeneic: See “Transplant.”

Systemic lupus erythematosus (SLE): See “Lupus.”

System for Thalidomide Education and Prescribing Safety (S.T.E.P.S.®) program: A program designed for doctors, nurses, pharmacists, and patients to ensure that developing fetuses are not exposed to thalidomide.

Systemic treatment: Treatment using substances that travel through the blood­stream to reach and affect cells in the entire body.

T-cells (T-lymphocytes): A type of white blood cell that plays a central role in the immune system. T cells can be distinguished from other lymphocytes, such as B cells and natural killer cells (NK cells), by the presence of a T-cell receptor (TCR) on the cell surface. They are called T cells because they mature in the thymus (although some also mature in the tonsils).

Thoracic spine: Twelve thoracic verte­brae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae.

Thrombocytes: See “Platelets.”

Thrombocytopenia: A low number of platelets in the blood. The normal level is 150,000–250,000. If the platelet count is less than 50,000, bleeding problems could occur. Major bleeding is usually associated with a reduction to less than 10,000.

Toxins: Poisons produced by certain animals, plants, or bacteria.

Transfusion: The transfer of blood or blood products.

Transplant (transplantation): There are several different types of transplantation.

Bone marrow transplant – This term refers to the process of collecting stem cells from the bone marrow and infusing them into a patient. This term is used less frequently today in myeloma as stem cells are now collected from the peripheral or circulating blood.

Peripheral blood stem cell (PBSC) transplant – Doctors remove healthy stem cells from a patient’s circulating blood system (not from the bone marrow) and store them before the patient receives high-dose chemotherapy to destroy the cancer cells. The stem cells are then returned to the patient, where they can produce new blood cells to replace cells destroyed by the treatment. Using PBSC for transplantation allows for easier and safer collection of stem cells and faster recovery after the transplant than bone marrow transplant.

Allogeneic (allograft) transplant – The infusion of bone marrow or stem cells from one individual (donor) to another (recipient). A patient receives bone marrow or stem cells from a compatible, though not genetically identical, donor. An HLA blood test is done to determine if a patient has a potential donor match. A donor may be a family member or may be obtained through a donor registry such as the National Marrow Donor Program (NMDP). Rarely, donor cells may be obtained from an umbilical cord blood bank. .

Autologous transplant – A procedure in which stem cells are removed from a patient’s blood and then are given back to the patient following intensive treatment.

Reduced-intensity conditioning (RIC) allo transplant – A newer and, for myeloma, safer technique than an allogeneic transplant. RIC is a non-myeloablative, reduced-intensity “mini-allo” transplant performed within 180 days after a standard autologous transplant.

Tandem transplant – A term used to indicate two transplants. This may be two autologous transplants or an autologous transplant followed by an allogeneic (donor) transplant. Tandem transplants are usually planned at three to six month intervals between transplants.

Matched unrelated donor (MUD) transplant – Refers to a stem cell transplantation procedure in which the patient and the stem cells are genetically matched but are not from family members. This procedure is not recommended for myeloma patients because it carries an unacceptably high mortality rate.

Syngeneic transplant – The infusion of bone marrow or stem cells from one identical twin into another.

Umbilical cord blood transplant – Stem cells obtained from the umbilical cords of newborns. These are frozen and stored in cord blood banks.

Tumor: An abnormal mass of tissue that results from excessive cell division.

Tumor lysis syndrome (TLS): A disorder caused by the break-down products of dying cancer cells, which can lead to kidney failure.

Tumor marker: A substance in blood or other body fluids that may suggest that a person has cancer.

Tumor necrosis factor (TNF): A type of biological response modifier that can improve the body’s natural response to disease.

Umbilical cord blood transplant: See “Transplant.”

Vaccine: A preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms that is administered to produce or artificially increase immunity to a particular disease.

Vascular endothelial growth factor (VEGF): A growth factor that promotes the growth of new blood vessels (angiogenesis).


Venous thromboembolism (VTE): A condition that includes both deep vein thrombosis (DVT) and pulmonary embolism (PE). Nearly two thirds of VTE events result from hospitalization. Risk factors include infection, age >75, cancer, and a history of VTE. See "Deep vein thrombosis (DVT)" and "Pulmonary embolism (PE)."


Vertebra: Any one of the 33 bony seg­ments of the spinal column.


Vertebral body: The round bony area of a vertebra.

Virus: A small living particle that can infect cells and change how the cells function. Infection with a virus can cause a person to develop symptoms. The disease and symptoms that are caused depend on the type of virus and the type of cells that are infected.

Waldenström’s macroglobulinemia: A rare type of indolent lymphoma that affects plasma cells. Excessive amounts of IgM protein are produced. Not a type of myeloma.

White blood cells (WBC): General term for a variety of cells responsible for fighting invading germs, infection, and allergy-causing agents. These cells begin their development in the bone marrow and then travel to other parts of the body. Specific white blood cells include neutrophils, granulocytes, lymphocytes, and monocytes.

X-ray: High-energy electromagnetic radiation used in low doses to diagnose diseases and in high doses to treat cancer.


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