Cancer Dictionary

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

M proteins: Antibodies or parts of antibodies found in unusually large amounts in the blood or urine of people with multiple myeloma.

mafosfamide: A form of cyclophosphamide that can be administered as an intrathecal infusion. Mafosfamide is being studied as an anticancer drug; it belongs to the family of drugs called alkylating agents.

MAGE-3: A gene found in some types of tumors.

magnetic resonance imaging (mag-NET-ik REZ-o-nans IM-a-jing): MRI. A procedure in which a magnet linked to a computer is used to create detailed pictures of areas inside the body.

maintenance therapy: Treatment that is given to help a primary (original) treatment keep working. Maintenance therapy is often given to help keep cancer in remission.

malabsorption syndrome: A group of symptoms such as gas, bloating, abdominal pain and diarrhea resulting from the body's inability to properly absorb nutrients.

malignancy: A cancerous tumor that can invade and destroy nearby tissue and spread to other parts of the body.

malignant (ma-LIG-nant): Cancerous; a growth with a tendency to invade and destroy nearby tissue and spread to other parts of the body.

malignant ascites: A condition in which fluid containing cancer cells collects in the abdomen.

malignant fibrous histiocytoma: A sarcoma that usually begins in soft tissue. It usually appears as an enlarging, painful mass that can cause fracture due to destruction of the bone by a spreading tumor.

malignant meningioma: A rare, quickly growing tumor that occurs in the membranes that cover and protect the brain and spinal cord (meninges).

malignant mesothelioma: A rare type of cancer in which malignant cells are found in the sac lining the chest or abdomen. Exposure to airborne asbestos particles increases one's risk of developing malignant mesothelioma.

MALT lymphoma: Mucosa-associated lymphoid tissue lymphoma. A type of cancer that arises in cells in mucosal tissue that are involved in antibody production.

mammogram (MAM-o-gram): An x-ray of the breast.

mammography (mam-OG-ra-fee): The use of x-rays to create a picture of the breast.

mantle field (MAN-tul): The area of the neck, chest and lymph nodes in the armpit that are exposed to radiation.

marimastat: An anticancer drug that belongs to the family of drugs called angiogenesis inhibitors. Marimastat is a matrix metalloproteinase inhibitor.

marker: A diagnostic indication that disease may develop.

mastectomy (mas-TEK-toe-mee): Surgery to remove the breast (or as much of the breast tissue as possible).

M.D.L 101,731: A drug that belongs to a family of drugs called ribonucleotide reductase inhibitors.

measurable disease: A tumor that can be accurately measured in size. This information can be used to judge response to treatment.

mechlorethamine: An anticancer drug that belongs to the family of drugs called alkylating agents.

medial supraclavicular lymph nodes: Lymph nodes located above the collar bone and between the center of the body and a line drawn through the nipple to the shoulder.

median: A statistics term. The middle value in a set of measurements.

mediastinoscopy (MEE-dee-a-stin-AHS-ko-pee): A procedure in which a tube is inserted into the chest to view the organs in the area between the lungs and nearby lymph nodes. The tube is inserted through an incision above the breastbone. This procedure is usually performed to get a tissue sample from the lymph nodes on the right side of the chest.

mediastinum (mee-dee-a-STYE-num): The area between the lungs. The organs in this area include the heart and its large blood vessels, the trachea, the esophagus, the bronchi and lymph nodes.

medical castration: Refers to the use of drugs to suppress the function of the ovaries or testicles.

medical oncologist (on-KOL-o-jist): A doctor who specializes in diagnosing and treating cancer using chemotherapy, hormonal therapy and biological therapy. A medical oncologist often serves as the main caretaker of someone who has cancer and coordinates treatment provided by other specialists.

medroxyprogesterone: A hormonal anticancer drug that is also used in cancer prevention. It belongs to the family of drugs called progestins.

medulloblastoma (MED-yoo-lo-blas-TOE-ma): A malignant brain tumor that begins in the lower part of the brain and can spread to the spine or to other parts of the body. Medulloblastomas are sometimes called primitive neuroectodermal tumors (PNET).

megestrol: A drug that belongs to the group of hormones called progestins, used as hormone therapy to block estrogen and to suppress the effects of estrogen and androgens. It is also used to stimulate the appetite in people with cancer.

melanin (MEL-a-nin): The substance that gives the skin its color.

melanocytes (mel-AN-o-sites): Cells in the skin that produce and contain the pigment called melanin.

melanoma: A form of skin cancer that arises in melanocytes, the cells that produce pigment. Melanoma usually begins in a mole.

melanoma vaccine: A cancer vaccine prepared from human melanoma cancer cells. It can be used alone or with other therapy in treating melanoma.

melphalan: An anticancer drug that belongs to the family of drugs called alkylating agents.

membrane: A very thin layer of tissue that covers a surface.

MEN-10755: An anticancer drug that belongs to the family of drugs called antitumor antibiotics.

meningeal: Refers to the meninges, the tissue covering the brain and spinal cord.

meningeal metastases: Cancer that has spread from the original (primary) tumor to the tissue covering the brain, spinal cord, or both.

meninges (meh-NIN-jeez): The three membranes that cover and protect the brain and spinal cord.

meningioma (meh-nin-jee-O-ma): A type of tumor that occurs in the meninges, the membranes that cover and protect the brain and spinal cord. Meningiomas usually grow slowly.

menopause (MEN-o-pawz): The time of life when a woman's menstrual periods stop permanently. Also called "change of life."

menstrual cycle (MEN-stroo-al): The monthly cycle of hormonal changes from the beginning of one menstrual period to the beginning of the next.

menstruation: Periodic discharge of blood and tissue from the uterus. Until menopause, menstruation occurs approximately every 28 days when a woman is not pregnant.

mercaptopurine: An anticancer drug that belongs to the family of drugs called antimetabolites.

Merkel cell cancer: A rare type of cancer that develops on or just beneath the skin.

mesenchymal: Refers to cells that develop into connective tissue, blood vessels and lymphatic tissue.

mesna: A drug that helps protect the kidneys and bladder from the toxic effects of anticancer drugs such as ifosfamide and cyclophosphamide.

metabolism: The total of all chemical changes that take place in a cell or an organism. These changes produce energy and basic materials needed for important life processes.

metaplasia: A change of cells to a form that does not normally occur in the tissue in which it is found.

metastasis (meh-TAS-ta-sis): The spread of cancer from one part of the body to another. Tumors formed from cells that have spread are called "secondary tumors" and contain cells that are like those in the original (primary) tumor. The plural is metastases.

metastasize (meh-TAS-ta-size): 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.

metastatic cancer: Cancer that has spread from the place in which it started to other parts of the body.

methotrexate: An anticancer drug that belongs to the family of drugs called antimetabolites.

methoxsalen: A drug used in ultraviolet light therapy.

methylphenidate: A drug that is a central nervous system stimulant.

methylprednisolone: A corticosteroid hormone replacement.

metoclopramide: A drug that prevents or reduces nausea and vomiting.

metronidazole: A drug used to treat bacterial, fungal and parasitic infections. It is also being studied in the treatment of some cancers.

MG98: An anticancer drug that belongs to the family of drugs called antisense compounds. These drugs interfere with production of certain proteins in the cell.

microcalcifications (MY-krow-kal-si-fi-KAY-shunz): Tiny deposits of calcium in the breast that cannot be felt but can be detected on a mammogram. A cluster of these very small specks of calcium may indicate that cancer is present.

mifepristone: An anticancer drug that blocks the action of progesterone, a hormone that affects the growth of some cancers.

mineral: A nutrient required to maintain health.

misoprostol: A radioprotective agent that belongs to the family of drugs called prostaglandins.

mistletoe lectin: A substance isolated from the mistletoe plant that is being studied as a treatment for cancer. A lectin is a complex molecule that has both protein and sugars. Lectins are able to bind to the outside of a cell and cause biochemical changes in it. Lectins are made by both animals and plants.

mitolactol: An anticancer drug that belongs to the family of drugs called alkylating agents.

mitomycin: An anticancer drug that belongs to the family of drugs called antitumor antibiotics.

mitotane: An anticancer drug used in treating adrenocortical cancer and ACTH-producing pituitary tumors (Cushing's disease).

mitotic inhibitors: Drugs that kill cancer cells by interfering with cell division (mitostis).

mitoxantrone: An anticancer drug that belongs to the family of drugs called antitumor antibiotics.

mivobulin isethionate: An anticancer drug that belongs to the family of drugs called mitotic inhibitors. Also called CI-980.

mixed gliomas: Brain tumors that occur in more than one type of brain cell, including astrocytes, ependymal cells and oligodendrocytes.

modified radical mastectomy (mas-TEK-toe-mee): Surgery for breast cancer in which the breast, some of the lymph nodes under the arm, the lining over the chest muscles and sometimes part of the chest wall muscles are removed.

molar pregnancy: A rare cancer in women of child-bearing age in which cancer cells grow in the tissues that are formed in the uterus after conception. Also called gestational trophoblastic disease, gestational trophoblastic neoplasia, gestational trophoblastic tumor, or choriocarcinoma.

mole: A benign growth on the skin (usually tan, brown, or flesh-colored) that contains a cluster of melanocytes and surrounding supportive tissue.

monoclonal antibodies (MAH-no-KLO-nul AN-tih-BAH-deez): Laboratory-produced substances that can locate and bind to cancer cells wherever they are in the body. Many monoclonal antibodies are used in cancer detection or therapy; each one recognizes a different protein on certain cancer cells. Monoclonal antibodies can be used alone, or they can be used to deliver drugs, toxins, or radioactive material directly to a tumor.

monoclonal antibody 3F8: A type of monoclonal antibody used in cancer detection or therapy. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells.

monocyte: A type of white blood cell.

Montanide ISA-51: A drug used in vaccine therapy to stimulate the immune system.

morphine: A narcotic drug used in the treatment of pain.

morphology: The science of the form and structure of organisms (plants, animals and other forms of life).

MRI: Magnetic resonance imaging (mag-NET-ik REZ-o- nans IM-a-jing). A procedure in which a magnet linked to a computer is used to create detailed pictures of areas inside the body.

MS 209: A substance that is being studied for its ability to make cancer cells respond better to chemotherapy drugs to which they have become resistant. It belongs to the family of drugs called quinolone antibiotics.

mucin/peptide: A protein/sugar compound made by some cancer cells.

mucositis: A complication of some cancer therapies in which the lining of the digestive system becomes inflamed. Often seen as sores in the mouth.

mucus: A thick, slippery fluid produced by the membranes that line certain organs of the body, including the nose, mouth, throat and vagina.

muJ591 monoclonal antibody: A type of monoclonal antibody used in cancer detection or therapy. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells.

multicenter study: A clinical trial that is carried out at more than one medical institution.

multidrug resistance: Adaptation of tumor cells to anticancer drugs in ways that make the drugs less effective.

multidrug resistance inhibition: Treatment used to make cancer cells less resistant to anticancer drugs.

multimodality treatment: Therapy that combines more than one method of treatment.

multiple myeloma (mye-eh-LO-ma): Cancer that arises in plasma cells (white blood cells that produce antibodies).

muromonab-CD3 monoclonal antibody: A type of monoclonal antibody used in cancer detection or therapy. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells.

musculoskeletal: Having to do with muscles, bones and cartilage.

mutation: Any change in the DNA of a cell. Mutations may be caused by mistakes during cell division, or they may be caused by exposure to DNA-damaging agents in the environment. Mutations can be harmful, beneficial, or have no effect. If they occur in cells that make eggs or sperm, they can be inherited; if mutations occur in other types of cells, they are not inherited. Certain mutations may lead to cancer or other diseases.

mycophenolate mofetil: A drug that is being studied for its effectiveness in preventing graft-versus-host disease and autoimmune disorders.

mycosis fungoides (mye-KO-sis fun-GOY-deez): A type of non-Hodgkin's lymphoma that first appears on the skin and can spread to the lymph nodes or other organs such as the spleen, liver, or lungs.

mycostatin: A drug that treats infections caused by fungi.

myelin (MYE-eh-lin): The fatty substance that covers and protects nerves.

myelodysplasia: Abnormal bone marrow cells that may lead to myelogenous leukemia.

myelodysplastic syndrome (MYE-eh-lo-dis-PLAS-tik SIN-drome): Disease in which the bone marrow does not function normally. Also called preleukemia or smoldering leukemia.

myelofibrosis: A disorder in which the bone marrow is replaced by fibrous tissue.

myelogenous (mye-eh-LAH-jen-us): Produced by, or originating in, the bone marrow.

myelogram (MYE-eh-lo-gram): An x-ray of the spinal cord after an injection of dye into the space between the lining of the spinal cord and brain.

myeloid (MYE-eh-loyd): Pertaining to, derived from, or manifesting certain features of the bone marrow. In some cases also pertains to certain types of non-lymphocyte white blood cells found in the bone marrow, including granulocyte, monocyte and platelet lineages. Also called myelogenous.

myeloma: Cancer that arises in plasma cells, a type of white blood cell.

myeloproliferative disorders: Diseases in which too many blood cells are made in the bone marrow.

myelosuppression: A condition in which bone marrow activity is decreased, resulting in fewer red blood cells, white blood cells and platelets. Myelosuppression is a side effect of some cancer treatments.

myelosuppressive therapy: Treatment that inhibits blood cell production.

myometrium (mye-o-MEE-tree-um): The muscular outer layer of the uterus.

Return to top of page

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

This cancer dictionary is provided by the National Cancer Institute.