• Abscess: A localized collection of pus that forms in tissues, organs or confined spaces as the body tries defending itself against infection-causing germs.
  • Adjuvant therapy: A treatment given in addition to the primary treatment (usually surgery) to make treatment more successful.
  • Antibody: A substance made by the body to fight infection.
  • Areola: The circular area of coloured skin surrounding the nipple.
  • Aspiration: Removal of fluid from a cyst or cells from a lump, using a needle and syringe.
  • Atypical hyperplasia: Cells that are both abnormal (atypical) and increased in number. This may moderately increase a woman’s risk of developing breast cancer.
  • Average risk (for breast cancer): A measure of the chances of getting breast cancer without the presence of any specific factors known to be associated with the disease.
  • Axilla: The armpit
  • Axillary dissection: Surgery in which a sample of the lymph nodes from the armpit are removed in order to find out if the cancer has spread.
  • Axillary lymph node: Located in the armpit, these glands help the body fight infection.


  • Benign: Non-cancerous; has not invaded nearby tissues or spread to other parts of the body.
  • Benign breast changes: Non-cancerous changes in the breast. May cause pain or lumpiness.
  • Biopsy: A procedure that involves the removal of a tissue sample of tissue or cells for microscopic analysis for purposes of diagnosis. Biopsies can be accomplished with a biopsy needle or open surgical incision.
  • BRCA1 and BRCA2 genes: The principal genes that, when altered, indicate an inherited susceptibility to breast cancer and possibly ovarian cancer. These gene alterations have been found to be present in 80 to 90 percent of hereditary cases of breast cancer.
  • Breast density: Glandular tissue in the breast common in younger women, making it difficult for mammography to detect breast cancer.
  • Breast implants: Silicone rubber sacs, which are filled with silicone gel or sterile saline, used for breast reconstruction after mastectomy.
  • BSE: Breast Self-Examination. An exam in which you feel for any changes in the breast. Regular BSE can help women to detect small changes in the look and feel of their breasts. Women over the age of 20 should perform this exam every month.


  • Calcifications: The process by which organic tissue becomes hardened by a deposit of calcium salts. These small calcium deposits can be seen on mammograms.
  • Cancer: A general name that comprises more than 100 diseases, characterized by an uncontrollable and abnormal growth of cells. Cancer cells invade and destroy healthy tissues, and may spread through the bloodstream and the lymphatic system to other parts of the body.
  • Carcinoma: Cancer that begins in tissues lining or covering the surfaces (epithelial tissues) of organs, glands, or other body structures. Most cancers are carcinomas.
  • Carcinoma in situ: Cancer that is found confined to the cells where it began, and has not spread into surrounding tissues.
  • Chemoprevention: The use of drugs or vitamins to prevent cancer in people who have precancerous conditions or a high risk of cancer, or to prevent the recurrence of cancer in people who have already been treated for it.
  • Chemotherapy: The use of anticancer drugs to kill cancer cells, which may have spread to other parts of the body. It is administered intravenously or given as pills.
  • Chromosomes: Structures located in the nucleus of a cell, containing genes.
  • Clinical breast exam: A physical exam performed by a doctor or nurse of the breast, underarm and collarbone area to feel for any changes in the breast.
  • Computed tomography (CT) scanning: An imaging technique that uses a computer to organize the information from multiple x-ray images to construct two dimensional cross-sectional image of areas inside the body. This can help reveal many soft tissue structures not shown by conventional radiography.
  • Computer-aided diagnosis (CAD): the use of special computer programs to scan mammographic images and flag areas that look suspicious.
  • Core needle biopsy: A procedure where use of a small cutting needle to remove a core of tissue for microscopic examination.
  • Cyclic breast changes: Normal tissue changes that occur in response to the changing levels of female hormones during the menstrual cycle, which can cause swelling, tenderness and pain.
  • Cyst: A fluid-filled sac, usually benign.


  • Diagnostic mammogram: The use of a breast x-ray to evaluate the breasts of a woman who has symptoms of disease such as a lump, or whose screening mammogram shows an abnormality.
  • Digital mammography: A technique for recording x-ray images in computer code, which allows the information to enhance subtle, but potentially significant, changes.
  • Ducts: Channels that carry body fluids – excretions or secretions. Breast ducts transport milk from the breast’s lobules out to the nipple.
  • Ductal carcinoma in situ (DCIS): Cancer that is confined to the ducts of the breast tissue and has not spread to surrounding tissue.
  • Ductogram: A test that helps determine the cause of a nipple discharge.
  • Dysplastic cells: Abnormal cells which could eventually become cancerous.


  • Excisional biopsy: The surgical removal (excision) of an abnormal or suspicious area of tissue, or lump by cutting the skin and removing the tissue for microscopic examination. Excisional biopsies remove the entire lump from the breast.
  • Estrogen: The female sex hormone which develops the female secondary sex characteristics and has a variety of functions during the menstrual cycle.
  • Estrogen replacement therapy: The use of estrogen in order to lessen the effects of being deficient in this hormone. (see Hormone replacement therapy)


  • False negative (mammograms): Breast x-rays that miss cancer when it is present.
  • False positive (mammograms): Breast x-rays that indicate breast cancer is present when the disease is truly absent.
  • Fat necrosis: Lumps of fatty material that forms in response to a bruise or blow to the breast.
  • Fibroadenoma: Benign breast tumor made up of both structural (fibro) and glandular (adenoma) tissues.
  • Fibrocystic changes: Benign changes in the breast.
  • Fine needle aspiration: A method in which fluid is removed from a cyst or cluster of cells from the affected area of the breast using a slender needle.
  • Fine needle aspiration biopsy: A biopsy which uses a syringe with a thin needle to remove small tissue fragments from a tumour.
  • Five-year survival rate: This refers to the percent of patients who live at least five years after their cancer is found.
  • Frozen section: A sliver of frozen biopsy tissue. A frozen section provides a quick preliminary diagnosis but is not 100 percent reliable.


  • Generalized breast lumpiness: Breast irregularities and lumpiness, commonplace and noncancerous. Sometimes called “fibrocystic disease” or “benign breast disease.
  • Gene: Segment of a DNA molecule and the fundamental biological unit of heredity. It is responsible for the inherited characteristics that make beings different from one another.
  • Genetic testing: A method by which a woman learns if she is carrying a mutated gene which may increase her risk of breast cancer.
  • Genetic change: An alteration in a segment of DNA, which can disturb a gene’s behavior and sometimes leads to disease.
  • Glands: Organs in the body which secrete a substance.


  • Higher risk (for breast cancer): A measure of the chances of getting breast cancer when factor(s) known to be associated with the disease are present.
  • Hormone replacement therapy: Hormone-containing medications taken to offset the symptoms and other effects of the hormone loss that accompanies menopause.
  • Hormones: A substance secreted by various glands in the body, which produce specific effects on specific target organs and tissues.
  • Hormone receptors: Structures on cells to which hormones attach themselves, affecting the activity of that cell. If cancer cells have hormone receptors, they will usually respond to hormone therapy.
  • Hormonal therapy: A type of cancer therapy which prevents natural hormones from stimulating the growth of tumours.
  • Hyperplasia: Excessive growth of cells. Several types of benign breast conditions involve hyperplasia.


  • Incisional biopsy: The surgical removal of a portion of an abnormal area of tissue, by cutting into (incising) it, for microscopic examination.
  • Infection: Invasion of body tissues by microorganisms such as bacteria and viruses.
  • Infiltrating cancer: Cancer that has spread to nearby tissue, lymph nodes under the arm, or other parts of the body.
  • Infiltrating ductal carcinoma (IDC): Cancer that begins in a duct of the breast and spreads to the surrounding fatty tissue.
  • Infiltrating lobular carcinoma (ILC): Cancer that begins in the lobules of the breast and spreads to other parts of the body.
  • Inflammation: The body’s protective response to injury (including infection). Inflammation is marked by heat, redness, swelling, pain and loss of function.
  • Intraductal papilloma: A small wart-like growth that projects into a breast duct.
  • Invasive cancer: Cancer that has spread to nearby tissue, lymph nodes under the arm, or other parts of the body. (Same as Infiltrating cancer.)


  • Laser beam scanning: A technology being studied in research for breast cancer detection that shines a laser beam through the breast and records the image produced, using a special camera.
  • Lobes, lobules, bulbs: Milk-producing tissues of the breast. Each of the breast’s 15 to 20 lobes branches into smaller lobules and each lobule ends in scores of tiny bulbs. Milk originates in the bulbs and is carried by ducts to the nipple.
  • Lobular carcinoma in situ (LCIS): Cancer that is found only in the lobules of the breast and that has not spread to the surrounding fatty tissue.
  • Localization biopsy: The use of mammography to locate tissue containing an abnormality that can be detected only on mammograms, so it can be removed for microscopic examination.
  • Local radiation: The insertion of a pellet of radioactive material into the cancer in order to shrink or kill cancer cells.
  • Local therapy: A type of therapy use to treat the main or primary tumour and the area around it.
  • Lumpectomy: Surgery to remove only the cancerous breast lump and some of the surrounding tissue; usually followed by radiation therapy. Also called a partial mastectomy.
  • Lymphatic system: The tissues and organs that produce, store, and transport cells that fight infection and disease.
  • Lymph nodes: Glands that are part of the body’s defence system.
  • Lymphatic tissue: Tissue made up of white blood cells in the lymphatic system.
  • Lymphedema: A condition which occurs when the lymph node system is not draining enough fluid after some of the lymph nodes have been removed, resulting in fluid retention and swelling of the arm or hand.


  • Magnetic resonance imaging (MRI): A technique that uses a powerful magnet linked to a computer to create detailed pictures of areas inside the body.
  • Malignancy: State of being cancerous. Malignant tumours can spread to surrounding tissues and other parts of the body.
  • Malignant growth: A cancerous growth that has the potential to spread.
  • Mammary duct ectasia: A benign breast condition in which ducts beneath the nipple become dilated and sometimes inflamed, and which can cause pain and nipple discharge.
  • Mammogram: A low-dose x-ray used to examine unusual changes in the breast or to screen for abnormalities where no changes has been found.
  • Mammography: The examination of breast tissue using x-rays.
  • Mastectomy: Surgery to remove the entire breast (or as much of the breast as possible).
  • Mastitis: Infection of the breast. Mastitis is most often seen in nursing mothers.
  • Menopause: The time when a woman’s monthly menstrual periods cease, usually around the age of 50.
  • Metastatic: Cancer which has spread through blood vessels or lymphatic channels to distant sites in the body.
  • Menstrual cycle: The monthly cycle of discharge, during a woman’s reproductive years, of blood and tissues from the uterus.
  • Microcalcifications: Tiny deposits of calcium in the breast, which can show up on a mammogram. Certain patterns of microcalcifications are sometimes a sign of breast cancer.
  • Modified radical mastectomy: The removal of all breast tissue including the nipple, as well as some of the lymph nodes under the arm in order to see whether or not the cancer has spread.
  • Mutation: A change in the number, arrangement or molecular sequence of a gene.


  • Needle biopsy: Use of a needle to extract cells or bits of tissue for microscopic examination.
  • Nipple discharge: Fluid coming from the nipple.
  • Non-invasive cancer: Cancer that has not spread to surrounding tissue.
  • Nonpalpable cancer: Cancer in breast tissue that can be seen on mammograms but that cannot be felt.


  • One-step procedure: Biopsy and surgical treatment combined into a single operation.
  • Open biopsy: A lump or mass is removed along with the surrounding tissue.
  • Outpatient basis: Medical care provided to a patient who is not hospitalized.
  • Osteoporosis: A condition of mineral loss that causes a decrease in bone density and an enlargement of bone spaces, producing bone fragility. Certain treatments for breast cancer can impact a woman’s risk of developing osteoporosis.


  • Palpation: Use of the fingers to press body surfaces, so as to feel tissues and organs underneath. Palpating the breast for lumps is a crucial part of a physical breast examination.
  • Partial mastectomy: Surgery in which the breast lump and some of the surrounding tissue is removed, also called a lumpectomy.
  • Pathologist: A doctor who specializes in the diagnoses disease by studying cells and tissues changes under a microscope.
  • Permanent section: Biopsy tissue specially prepared and mounted on slides so that it can be examined under a microscope by a pathologist.
  • Phytochemicals: Naturally occurring chemicals found in plants that may be important nutrients for reducing a person’s cancer risk.
  • Positron emission tomography (PET scanning): A technique that uses signals emitted by radioactive tracers to construct images of the distribution of the tracers in the human body.
  • Prophylactic mastectomy: Surgery to remove a breast that is not known to contain breast cancer, for the purpose of reducing an individual’s cancer risk.
  • Prosthesis: An artificial substitute for a missing part of the body, for example the breast.


  • Radiation therapy: Radiation is energy carried by waves or by streams of particles. In radiation therapy, various forms of radiation can be used in low doses to diagnose disease and in high doses to treat disease. See X-rays.
  • Radical mastectomy: Removal of the entire breast, lymph nodes and the chest wall muscles.
  • Radiologist: A doctor with special training in the use of diagnostic imaging such as CT, MRI, PET and ultrasound, to image body tissues and to treat disease.
  • Reconstruction surgery: An operation in which a breast’s normal appearance is restored after a mastectomy.
  • Risk: A measure of the likelihood of some uncertain or random event with negative consequences for human life or health.
  • Risk factors (for cancer): Conditions or agents that increase a person’s chances of getting cancer. Risk factors do not necessarily cause cancer; rather, they are indicators, statistically associated with an increase in likelihood.


  • Saline implant: A sac filled with sterile saltwater inserted under the skin of the chest wall to restore or improve the shape of the breast.
  • Sclerosing adenosis: A benign breast disease that involves the excessive growth of tissues in the breast’s lobules.
  • Screening: The use of tests to detect a disease in people who do not have symptoms of that disease.
  • Screening mammogram: Breast x-ray used to look for signs of disease such as cancer in people who are symptom-free.
  • Sentinel lymph node biopsy: A new procedure which is used to find the lymph nodes that drain lymph fluid from the area where a cancer has developed. The lymph nodes are then checked for any spread of cancer.
  • Sonogram: The image produced by ultrasound.
  • Specimen x-ray: An x-ray of tissue that has been surgically removed (surgical specimen).
  • Staging: A system for analyzing a tumour to determine the extent or risk of spread or recurrence, and appropriate treatment choices.
  • Stereotactic localization biopsy: A technique that employs three-dimensional x-ray to pinpoint a specific target area. It is used in conjunction with needle biopsy of nonpalpable breast abnormalities.
  • Surgical biopsy: The surgical removal of tissue for microscopic examination and diagnosis. Surgical biopsies can be either excisional or incisional. (See Excisional biopsy and Incisional biopsy.)
  • Surgical breast oncologist: A doctor who specializes in the diagnosis and treatment of breast cancer.
  • Surgical oncologist: A physician specializing in the use of surgery to treat cancer.
  • Syndrome: A group of symptoms and findings detected by examinations or test.
  • Systemic disease: A disease affecting the whole body.
  • Systemic therapy: A type of therapy given through the bloodstream in the form of injections or pills in order to reach cancer cells that may have spread.


  • Tamoxifen: A drug prescribed to women with estrogen receptive tumours, in order to stop estrogen from entering the breast tissue. It is also being tested as a possible preventive strategy. Women on this medication should have regular ultrasounds of the endometrium (lining of the uterus) because of potential changes there.
  • Tumour: An abnormal growth of tissue resulting from excessive cell division. Tumors may be either benign or cancerous.
  • Tumour markers: Proteins (either amounts or unique variants) made by altered genes in cancer cells that are involved in the progression of the disease.
  • Two-step procedure: Biopsy and treatment done in two stages, usually a week or two apart.


  • Ultrasound: A diagnostic technique using sound waves produce images of body tissues, especially internal organs.
  • Ultrasound guided needle biopsy: A procedure where tissue is removed through a needle guided by ultrasound.


  • X-ray: A high-energy form of radiation. X-rays form an image of body structures by traveling through the body and striking a sheet of film. Breast x-rays are called mammograms.