Susan G Komen  
I've Been Diagnosed With Breast Cancer Someone I Know Was Diagnosed Share Your Story Join Us And Stay Informed Donate To End Breast Cancer
Home > Understanding Breast Cancer > Resources > Glossary




Clicking on most terms will take you to the related section of Understanding Breast Cancer.

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



Absolute Risk
A person's chance of developing a certain disease over a certain time period. The absolute risk of a disease is estimated by looking at a large group of people similar in some way (in terms of age, for example) and counting the number of people in this group who develop the disease over the specified time period. For example, if we followed 100,000 women between the ages of 30 and 34 for one year, about 25 would develop breast cancer. This means the one-year absolute risk of breast cancer for a 30- to 34-year-old woman is 25 per 100,000 women (1 per 4,000 women).

Use of very thin needles inserted at precise points on the body that may help control pain and other side effects of treatment or breast cancer itself. It is a type of integrative or complementary therapy.

Adjuvant (Systemic) Therapy
Treatment given in addition to surgery and radiation to treat breast cancer that may have spread to other parts of the body. It may include chemotherapy, targeted therapy and/or hormone therapy.

Advocacy (see Breast Cancer Advocacy)

Hair loss.

Alternative Therapy
Any therapy used instead of standard medical treatments such as surgery, chemotherapy and hormone therapy. Alternative therapies are different from integrative and complementary therapies, which are used in addition to standard treatments. Alternative therapies have not been shown to be effective in treating breast cancer, so it is not safe to use them.

The absence or stopping of menstrual periods. 

Loss of feeling or sensation that keeps a person from feeling pain during surgery or other medical procedures. Local or regional anesthesia may be used for a specific part of the body, such as the breast, by injection of a drug into that area. General anesthesia numbs the entire body and puts a person to sleep with drugs that are injected into a vein or inhaled.

Aneuploid (DNA Ploidy)
The presence of an abnormal number of chromosomes in cancer cells.

The growth of new blood vessels that cells need to grow.  

A protein made by white blood cells that is part of the body’s immune system. Each antibody binds to a certain antigen (foreign substance, such as bacteria) and helps the body fight the antigen.

Antibody Therapy
A drug containing an antibody that is specially made to target certain cancer cells. See Antibody.

An agent that counteracts carcinogens (cancer causing agents).

A medicine that prevents or relieves nausea and vomiting.

A substance that causes the body to make an immune response. This immune response often involves making antibodies.

A substance that protects the body from damage by oxidizing agents. Oxidizing agents are always present in the body and are often beneficial. However, when large amounts of oxidants are present in cells, they can cause damage, especially to DNA. This can lead to abnormal cell growth. Antioxidants include beta-carotene and vitamins A, C and E.

A normal cell process in which a genetically programmed series of events leads to the death of a cell. Cancer cells may block apoptosis.

The darkly shaded circle of skin surrounding the nipple.

Aromatase Inhibitors
Hormone therapy drugs that lower estrogen levels in the body by blocking aromatase, an enzyme that converts other hormones into estrogen. Aromatase inhibitors are used to treat postmenopausal women with hormone-receptor positive breast cancer.

To remove fluid and a small number of cells.

Atrophic Vaginitis (see Vaginal Atrophy

Atypical Hyperplasia
A benign (not cancer) breast condition where breast cells are growing rapidly (proliferating). The proliferating cells look abnormal under a microscope. Although atypical hyperplasia is not breast cancer, it increases the risk of breast cancer.

A blood donation or tissue graft from a person’s own body rather than from a donor. For example, autologous breast reconstruction techniques use skin and tissue flaps (grafts) from a person’s own body.

The underarm area.

Axillary Dissection (Axillary Sampling)
Surgical procedure to remove some or all of the lymph nodes from the underarm area so that the nodes can be examined under a microscope to check whether or not cancer cells are present.

Axillary Lymph Nodes
The lymph nodes in the underarm area.

An integrative or complementary medical system from India that involves diet, exercise, meditation and massage. Ayurveda means "life-knowledge."

Top of Document  



Not cancerous. Does not invade nearby tissue or spread to other parts of the body.

Benign Breast Conditions (Benign Breast Disease)
Noncancerous conditions of the breast that can result in lumps or other abnormalities. Examples include cysts and fibroadenomas.

Benign Phyllodes Tumor
A rare benign (not cancer) breast condition similar to a fibroadenoma. A lump may be felt, but is usually painless.   

Bilateral Prophylactic Mastectomy
Surgery where both breasts are removed to prevent breast cancer from developing.

Biobank (Tissue Repository)
A large collection of tissue samples and medical data that is used for research studies.  

Bioimpedance (Bioelectrical Impedance Analysis) 
A method of measuring the amount of fluid in body tissues.

Biological Therapy
A therapy that targets something specific to the biology of the cancer cell, as opposed to chemotherapy, which attacks all rapidly dividing cells. Often used to describe therapies that use the immune system to fight cancer (immunotherapy). Trastuzumab (Herceptin) is an example of a biological or targeted therapy agent.

A substance found in blood, other body fluids or tissues that can be measured and is a sign of disease or another process in the body (normal or abnormal). It also may be used to see how well the body responds to a treatment for a disease.  

Removal of tissue to be tested for cancer cells.

Drugs used to strengthen bones and decrease the rate of bone fractures and pain due to breast cancer metastases to the bone.

Body Mass Index (BMI)
A measure used to estimate body fat. BMI takes into account a person’s height and weight. Calculate your BMI.

Bone Scan
A test done to check for signs of cancer in the bones. A small amount of radioactive material is injected into the bloodstream. It collects in the bones, especially abnormal areas, and is detected by a scanner. Bone scans can show cancer as well as benign bone diseases (like arthritis).

Additional dose of radiation to the part of the breast that had the tumor.

BRCA1/BRCA2 Genes (BReast CAncer genes)
Genes that help limit cell growth. A mutation (change) in one of these genes increases a person’s risk of breast, ovarian and certain other cancers.

A procedure that uses targeted radiation therapy from inside the tumor bed.

Breast Cancer
An uncontrolled growth of abnormal breast cells.

Breast Cancer Advocacy
Influencing targeted audiences to promote the support of breast cancer issues.

Breast Cancer Survivor (see Survivor)

Breast Conserving Surgery (see Lumpectomy)   

Breast Density
A measure used to describe the relative amounts of fat and tissue in the breasts as seen on a mammogram.

Breast-Specific Gamma Imaging (see Nuclear Medicine Imaging of the Breast)

Breast Imaging Reporting and Data System (BI-RADS®)
A system developed by the American College of Radiology to provide a standard way to describe the findings on a mammogram. 

Breast Reconstruction
Surgery to restore the look and feel of the breast after mastectomy.

Breast Self-Examination (BSE)
A method that may help women become familiar with the normal look and feel of their breasts. BSE is not recommended as a breast cancer screening tool because it has not been shown to decrease breast cancer death.

Breast Tomosynthesis (3D Digital Mammography, Digital Tomosynthesis)
A tool that uses a digital mammography machine to take multiple two dimensional (2D) X-ray images of the breast. Computer software combines the multiple 2D images into a three dimensional image. Breast tomosynthesis is not a standard breast cancer screening tool at this time.

Top of Document  



Loss of appetite and weight. 

Deposits of calcium in the breast that appear as bright, white spots on a mammogram. Most calcifications are not cancer. However, tight clusters or lines of tiny calcifications (called microcalcifications) can be a sign of breast cancer.

General name for over 100 diseases with uncontrolled cell growth.

Cancer Staging (see Staging) 

Carcinoma in Situ (in Situ Carcinoma)
Condition where abnormal cells are found in the milk ducts or lobules of the breast, but not in the surrounding breast tissue. In situ means "in place." See ductal carcinoma in situ and lobular carcinoma in situ.

Case-Control Study
An observational study that looks at two groups–one with people who already have the outcome of interest (cases), and one with people who do not (controls). For example, the cases may be women with breast cancer and the controls may be cancer-free women. The two groups are then compared to see if any characteristic was more common in the past history of one group compared to the other. 

Case Series
A health care provider’s observations of a group of patients who are given a certain type of treatment.

A small tube used to deliver fluids to (or remove them from) the body.

Centigray (Centigrays)
One centigray describes the amount of radiation absorbed by the body and is equivalent to 1 RAD (radiation absorbed dose).

A drug or combination of drugs used to lower the risk of breast cancer in cancer-free women at higher risk.

A drug or combination of drugs that kills cancer cells in various ways.

Clinical Breast Examination (CBE)
A physical exam done by a health care provider to check the look and feel of the breasts and underarm for any changes or abnormalities (such as lumps).

Clinical Trials
Research studies that test the benefits of possible new ways to detect, diagnose, treat or prevent disease. People volunteer to take part in these studies.

Cognitive (function)
Mental processes related to understanding, such as reasoning and problem-solving.

Cohort Study
A study that follows a large group of people (a cohort) over time.

Co-Insurance (see Co-Payment)  

Complementary Therapies (Integrative Therapies) 
Therapies (such as acupuncture or massage) used in addition to standard medical treatments. Complementary therapies are not used to treat cancer, but they may help improve quality of life and relieve some side effects of treatment or the cancer itself. When complementary therapies are combined with standard medical care, they are often called integrative therapies.

Computerized Axial Tomography (CAT) Scan (see CT Scan)

95% Confidence Interval (95% CI) 
A statistical concept that shows there is a 95 percent probability the 'true' measure is found within a range of measures computed from a single study. For example, if the 95% confidence interval for a survival rate is 75 to 90 percent, there is a 95 percent chance the true survival rate falls between 75 and 90 percent.  

Co-Payment (Co-Insurance) 
In an insurance plan, the portion of medical costs a person must pay (the portion not covered by his/her insurance policy).

Core Needle Biopsy
A needle biopsy that uses a hollow needle to remove samples of tissue from an abnormal area in the breast.

A person who lends support to someone diagnosed with breast cancer, from the time of diagnosis through treatment and beyond. Co-survivors may include family members, spouses or partners, friends, health care providers and colleagues. 

CT Scan (Computerized Tomography Scan, Computerized Axial Tomography (CAT) Scan)
A series of pictures created by a computer linked to an X-ray machine. The scan gives detailed internal images of the body.

Cumulative Risk
The sum of a person's chances of developing a disease (like breast cancer) over the course of a lifetime (usually defined as birth up to age 85). For example, the cumulative (lifetime) risk of breast cancer for women is about 1 in 8 (or about 12 percent). This means for every 8 women, one will be diagnosed with breast cancer during her lifetime (up to age 85).  

A fluid-filled sac.

A pathologist who specializes in looking at individual cells. A cytopathologist is needed to interpret the results of fine needle aspiration.

Toxic, or deadly, to cells (cell killing). Often used to describe chemotherapy.

Top of Document  



Deductible (Insurance Deductible) 
The pre-set amount of medical costs a person must pay before insurance payments begin.

Definitive Surgery 
All of the known tumor is removed and no follow-up surgery is needed.

Diabetic Mastopathy
A rare benign (not cancer) breast condition that consists of small hard masses in the breast. It occurs most often in women with insulin-dependent (type 1) diabetes.  

Identification of a disease from its signs and symptoms.

Diagnostic Mammogram
A mammogram used to check symptoms of breast cancer (such as a lump) or an abnormal finding noted on a screening mammogram or clinical breast exam. It involves two or more X-ray views of the breast.

Diagnostic Radiologist (Radiologist)
A health care provider who specializes in the diagnosis of diseases using X-rays.

Diploid (DNA Ploidy)
The presence of a normal number of chromosomes in cancer cells.

Disease-Free Survival Rate
Percent of people alive and without disease at a certain time (often five years or 10 years) after treatment. Those who die from causes other than the disease under study are not included in this measure.

Distant Recurrence (see Metastases)

DNA (Deoxyribonucleic Acid)
The information contained in a gene.  

Dose-Dense Therapy 
Chemotherapy given over a shorter (more condensed) time period compared to standard therapy. The frequency of treatment sessions is increased, so the length of the treatment period is shortened.  

Lowering the stage of a cancer from its original stage (or the stage it was thought to be). Down-staging occurs most often after a good response to neoadjuvant therapy. Neoadjuvant therapy is chemotherapy or hormone therapy used as a first treatment (before surgery) for some large or advanced breast cancers. Neoadjuvant therapy can shrink a tumor such that it lowers the stage of the breast cancer and a lumpectomy, instead of a mastectomy, can be done.  

Duct (Milk Duct, Mammary Duct) 
A canal that carries milk from the lobules to a nipple opening during breastfeeding (see figure). 

Ductal Carcinoma in Situ (DCIS, Intraductal Carcinoma)
A non-invasive breast cancer that begins in the milk ducts of the breast, but has not invaded nearby breast tissue. Also called stage 0 or pre-invasive breast carcinoma.

Ductal Papilloma (see Intraductal Papilloma)  

Top of Document  



Early Breast Cancer
Cancer that is contained in the breast or has only spread to lymph nodes in the underarm area. This term often describes stage I and stage II breast cancer.

Excess fluid in body tissues that causes swelling.

Endocrine Manipulation (see Hormone Therapy)

Endometrial Cancer
Cancer of the endometrium (the lining of the uterus).

A protein that speeds up biologic reactions in the body. 

The study of the causes and prevention of disease.

The most biologically active, naturally occurring estrogen in women.

A female hormone produced by the ovaries and adrenal glands that is important to reproduction. Some cancers need estrogen to grow.

Estrogen Receptors
Specific proteins in cells that estrogen hormones attach to. A high number of estrogen receptors on a breast cancer cell often means the cancer cell needs estrogen to grow.

The cause(s) of a disease.  

Excisional Biopsy
Surgical procedure that removes the entire abnormal area (plus some surrounding normal tissue) from the breast.

External Beam Radiation Therapy (see Radiation Therapy)

Top of Document  



False Negative
A test result that incorrectly reports a person is disease-free when she/he actually has the disease.

False Positive
A test result that incorrectly reports a person has a disease when she/he does not have the disease.

Family History (Family Medical History)
A record of the current and past health conditions of a person’s biological (blood-related) family members that may help show a pattern of certain diseases within a family.  

Fat Necrosis 
A benign (not cancer) breast change in which the breast responds to trauma with a firm, irregular mass, often years after the event. The mass is the result of fatty tissue dying, after either surgery or blunt trauma to the breast. This breast change does not increase risk of breast cancer.

A benign (not cancer) fibrous tumor that may occur at any age, but is more common in young adulthood.

Fibrocystic Condition (Fibrocystic Changes)
A general term used to describe a benign (not cancer) breast condition that may cause painful cysts or lumpy breasts.

Fine Needle Aspiration (FNA, Fine Needle Biopsy)
A biopsy procedure that uses a thin, hollow needle to remove a sample of cells from the abnormal area of the breast.

First-Degree Relative (Immediate Family Member)
A person’s mother, father, sister, brother or child.

First-Line Therapy
The initial (first) therapy used in a person’s cancer treatment.

Flow Cytometry
A laboratory test done on tumor tissue to measure the growth rate of the cancer cells and to check if the cells have too much DNA.

Fluorescence In Situ Hybridization (FISH)
A laboratory test done on breast tumor tissue to find out the number of copies of the HER2/neu gene contained in the cancer cells.

Frozen Section 
Process where a portion of tissue from a surgical biopsy is frozen so a thin slice can be studied to check for cancer. Frozen section results are only preliminary and always need to be confirmed by other methods.

Top of Document  



Gail Model (Breast Cancer Risk Assessment Tool)
A tool that uses personal and family history to estimate a woman’s risk of invasive breast cancer.

A milk-filled cyst.

The part of a cell that contains DNA. The DNA information in a person's genes is inherited from both sides of a person’s family.

Gene Expression
Process in which a gene gets turned on in a cell to make RNA and proteins.

Gene Expression Profiling (see Tumor Profiling)

Gene Mutation
Any change in the DNA (the information contained in a gene) of a cell. Gene mutations can be harmful, beneficial or have no effect.

Gene Variant of Uncertain Significance
A gene mutation not currently known to increase breast cancer risk.

General Practitioner (Internist, Physician)
The personal or family physician who may first find a suspicious area in the breast through a clinical breast exam or mammogram.

The chemical name of a drug, not the brand name. The chemical formulations of a generic drug and the brand name drug are the same.  

Genetic (Hereditary)
Related to genes. The information in a person’s genes can be passed on (inherited) from either parent.

Genetic Susceptibility (Genetic Predisposition)
An increased likelihood or chance of developing a disease due to specific changes in a person's genes passed on from either parent.  

Genetic Testing
Analyzing DNA to look for a gene mutation that may show an increased risk for developing a specific disease.  

The total genetic information of an organism.  

The study of genes and their functions.

Grade (see Tumor Grade)

Guaranteed Renewable Insurance
A health insurance policy that requires the insurance company to renew your policy for a certain amount of time, even if your health condition changes.

Top of Document  



H&E (Hematoxylin and Eosin) Staining
A laboratory test that gives color to cells so cell structures can be identified.

HER2/neu (Human Epidermal Growth Factor Receptor 2, erbB2) 
A protein that appears in high numbers on the surface of the breast cancer cells of about 15 to 20 percent of people with breast cancer. Tumors with high levels of HER2/neu can be treated with the targeted therapy drug trastuzumab (Herceptin). 

Herceptin (see Trastuzumab)  

Hereditary (see Genetic)  

Homeopathy (Homeopathic Medicine)
A medical system based on a belief that “like cures like.” Natural substances are specially prepared in small amounts to restore health. These substances cause symptoms similar to the condition they are meant to treat in healthy people. There are limited data on the safety of these substances.

Chemicals made by certain glands and tissues in the body, often in response to signals from the pituitary gland or the adrenal gland. Hormones have specific effects on specific target organs and tissues. Examples include estrogen and progesterone. Hormones can also be made in a laboratory.

Hormone Receptors 
Specific proteins on cells that hormones attach to. A high number of hormone receptors on a breast cancer cell often means the cancer cell needs the hormone to grow.

Hormone Receptor Status
Shows whether or not a breast cancer needs hormones to grow. A hormone receptor-positive cancer needs hormones to grow. A hormone receptor-negative cancer does not need hormones to grow. See Hormone Receptor.

Hormone Replacement Therapy (see Menopausal Hormone Therapy)    

Hormone Therapy (Endocrine Therapy, Endocrine Manipulation) 
Treatment that works by keeping cancer cells with hormone receptors from getting the hormones they need to grow.

A philosophy of care focusing on improving quality of life and easing pain and other symptoms at the end stage of a terminal illness. Hospice care also provides support services to patients and their families.

Hyperplasia (Usual and Atypical Hyperplasia)
A benign (not cancer) breast condition where breast cells are growing rapidly (proliferating). Although hyperplasia is not breast cancer, it increases the risk of breast cancer. In usual hyperplasia, the proliferating cells look normal under a microscope. In atypical hyperplasia, the proliferating cells look abnormal. 

Top of Document  



Immediate Family Member (First-Degree Relative)
A person’s mother, father, sister, brother or child.

Therapies that use the immune system to fight cancer. These therapies target something specific to the biology of the cancer cell, as opposed to chemotherapy, which attacks all rapidly dividing cells. See Biological Therapy.

Immunohistochemistry (IHC)
A laboratory test done on tumor tissue to detect the amount of HER2/neu protein on the surface of the cancer cells.

Implant (Breast Implant)
An "envelope" containing silicone, saline or both, that is used to restore the breast form after a mastectomy (or for other cosmetic reasons).

In Situ Carcinoma (see Carcinoma in Situ)  

In-Network Provider
The health care providers and medical centers (hospitals and other treatment centers) that are part of a particular group health plan or health maintenance organization (HMO).

The number of new cases of a disease that develop in a specific time period.

Incisional Biopsy
Surgical biopsy that removes only part of the tumor.

Indemnity Policy 
A prepayment insurance plan that gives services or a cash payment for medical care needed in times of illness or disability.

Induction Chemotherapy (see Neoadjuvant Chemotherapy)

Inflammatory Breast Cancer (IBC)
A rare and aggressive form of invasive breast cancer. Its main symptoms are swelling (inflammation) and redness of the breast. The skin on the breast may look dimpled, like the skin of an orange, and may be warm to the touch.

Informed Consent
The process through which a person learns about the possible benefits and side effects of a treatment plan and then accepts or declines the treatment. The person is usually asked to sign a consent form, but may stop the treatment at any time and get other medical care.

Infraclavicular Lymph Nodes
The lymph nodes below the clavicle (collarbone). See Lymph Nodes.

Insurance Payment Cap
A maximum amount an insurance company will pay out in a given time period.

Insurance Premium (Premium)
The cost of insurance coverage for a certain period of time.

Integrative Therapies (see Complementary Therapies

Within the milk duct. Intraductal can describe a benign (not cancerous) or malignant (cancerous) process.

Intraductal Hyperplasia
An excess of cells growing within the milk ducts of the breast. 

Intraductal Papilloma (Ductal Papilloma)
Small, benign (not cancer) growths that begin in the ducts of the breast and usually cannot be felt. Symptoms include a bloody or clear nipple discharge.  

Intravenous or IV
Being within or entering the body through the veins. 

Invasive Breast Cancer
Cancer that has spread from the original location (milk ducts or lobules) into the surrounding breast tissue and possibly into the lymph nodes and other parts of the body. Invasive ductal cancer begins in the milk ducts. Invasive lobular cancer begins in the lobules of the breast. 

Investigational New Drug (New Experimental Treatment)
A chemical or biological drug that has been approved for use by researchers in studies, but is not yet available outside of a clinical trial.

Top of Document 



Ki-67 Rate
A common way to measure proliferation rate. The more cells the Ki-67 antibody attaches to on a tissue sample, the more likely the tumor cells are to grow and divide rapidly.  

Top of Document 



The process of producing milk and breastfeeding a child.

Large Veins (Deep Veins)
The large veins deep inside the legs that carry blood from the legs back to the heart.

Late-Stage Cancer (see Metastatic Breast Cancer)

Area of abnormal tissue.

Lifetime Risk
The chance of developing a disease (like breast cancer) over the course of a lifetime (usually defined as birth up to age 85). For example, the lifetime risk of breast cancer for women is 1 in 8 (or about 12 percent). This means for every 8 women, one will be diagnosed with breast cancer during her lifetime (up to age 85).

Linear Accelerator
The device used during radiation therapy to direct X-rays into the body.

Liver Scan
An image of the liver that can show the presence or absence of a tumor.  

Lobular Carcinoma in Situ (LCIS, Lobular Neoplasia in Situ)
A condition where abnormal cells grow in the lobules of the breast. LCIS increases the risk of breast cancer.

Lobular Neoplasia in Situ (see Lobular Carcinoma in Situ)

Ball-shaped sacs in the breast that produce milk.

Local Anesthetic
Anesthesia that only numbs the tissue in a certain area. See Anesthesia.

Local Treatment
Treatment that focuses on getting rid of the cancer from a certain (local) area. In breast cancer, the local area includes the breast, the chest wall and lymph nodes in the underarm area (axillary nodes). Local treatment for breast cancer includes surgery with or without radiation therapy.

Localized Breast Cancer
Cancer that is contained in the breast and has not spread to nearby tissue, lymph nodes or other organs.

Locally Advanced Breast Cancer (Stage III Breast Cancer)
Cancer that has spread beyond the breast to the skin or chest wall, but not to distant organs like the lungs or liver. It also refers to a tumor that is larger than five centimeters (about two inches) in size.

Local Recurrence (Recurrence)
The return of cancer to the same breast or to the same side chest wall.

Any mass in the breast or elsewhere in the body.

Lumpectomy (Breast Conserving Surgery)
Surgery that removes only part of the breast—the part containing and closely surrounding the tumor. 

Lymph Nodes (Lymph Glands)
Small groups of immune cells that act as filters for the lymphatic system. Clusters of lymph nodes are found in the underarms, groin, neck, chest and abdomen.  

Lymph Node Status
Shows whether or not cancer has spread to the lymph nodes. Lymph node-positive means that cancer has spread to the lymph nodes. Lymph node-negative means that cancer has not spread to the lymph nodes. See Lymph Nodes.

Lymphatic System
The network of lymph nodes and vessels in the body.  

Swelling due to poor draining of lymph fluid that can occur after surgery to remove lymph nodes or after radiation therapy to the area. Most often occurs in the upper limbs (arm, hands or fingers), but can occur in other parts of the body.  

Top of Document  



Macrobiotics (Macrobiotic Diet)
Integrative or complementary dietary therapy that includes a mostly vegetarian, organic food diet with certain methods of food preparation.

Magnetic Resonance Imaging (see MRI)  


Mammary Duct (see Duct

Mammary Duct Ectasia
A benign (not cancer) breast condition resulting from inflammation (swelling) and enlargement of the ducts behind the nipple. Often there are no symptoms, but calcifications seen on a mammogram may point to its presence. No treatment is needed if the woman is not having symptoms (burning, pain or itching in the nipple area).

Mammary Glands
The breast glands that produce milk.

An X-ray image of the breast.

The rim of normal tissue surrounding a tumor that has been surgically removed. A margin is clean (also known as uninvolved, negative or clear) if there is only normal tissue (and no cancer cells) at the edges. Clean margins show the entire tumor was removed. With involved (also known as positive) margins, normal tissue does not completely surround the tumor. This means the entire tumor was not removed and more surgery is needed to get clean margins.

Surgical removal of the breast. The exact procedure depends on the diagnosis. See Total Mastectomy and Modified Radical Mastectomy.

An inflammation (swelling) of the breast usually occurring during breastfeeding. Symptoms include pain, nipple discharge, fever, redness and hardness over an area of the breast.

The average of a group of numbers.

Mean Survival Time
The average time from the start of treatment (or diagnosis) that people in a study stay alive.

The middle value (50th percentile) of a group of numbers.

Medical Oncologist
A physician specializing in the treatment of cancer using chemotherapy, hormone therapy and targeted therapy.

Hormone made by the pineal gland in the brain. It is an important part of the body's internal timing system.

The first menstrual period.  

Menopausal Hormone Therapy (Postmenopausal Hormone Use, Hormone Replacement Therapy)
The use of hormone pills containing estrogen (with or without progestin) to ease symptoms of menopause.

The ending of the normal menstrual cycle in women. It occurs most often in the late forties or early fifties.

A method for taking the results reported in a group of studies and averaging them to come up with a single, summary result.

The chemical process whereby drugs and food are broken down by the body. 

Spread of cancer to other organs through the lymphatic and/or circulatory system.

Small, clustered deposits of calcium in the breast that may be seen on a mammogram. These may or may not be related to breast cancer. 

Microvascular Surgery
Surgery that involves connecting small blood vessels.

Modified Radical Mastectomy
Surgical removal of the breast, the lining of the chest muscles and some of the lymph nodes in the underarm area. Used to treat early and locally advanced breast cancer.

Molecular Breast Imaging (see Nuclear Medicine Imaging of the Breast)  

Monoclonal Antibodies 
Immune proteins that can locate and bind to cancer cells. They can be used alone or they can be used to deliver drugs, toxins or radioactive material directly to tumor cells. Trastuzumab (Herceptin) is an example of a monoclonal antibody used to treat breast cancer.

Mortality Rate
Number of deaths in a given group of people over a certain period of time.  

MRI (Magnetic Resonance Imaging)
An imaging technique that uses a magnet linked to a computer to make detailed pictures of organs or soft tissues in the body.

mTOR (Mammalian Target of Rapamycin) Inhibitors
A class of targeted therapy drugs that may increase the benefit of hormone therapy. Everolimus (Afinitor) is an example of an mTOR inhibitor.

Multifocal Tumors (Multicentric Tumors)
One or more tumors that develop from the original breast tumor.

Multimodality Therapy
Use of two or more treatment methods (such as surgery, radiation therapy, chemotherapy, hormone therapy and targeted therapy) in combination or one after the other to get the best results.

Mutation (Gene Mutation)
Any change in the DNA (the information contained in a gene) of a cell. Gene mutations can be harmful, beneficial or have no effect.

Top of Document  



Naturopathy (Naturopathic Medicine)
A medical system based on a belief in using natural elements to maintain health and to help the body heal itself. It includes therapies such as nutrition and massage.

Needle Localization (see Wire Localization)  

Neoadjuvant Chemotherapy (Induction Chemotherapy, Primary Chemotherapy, Preoperative Chemotherapy)
Chemotherapy used as a first treatment. Often used for large or locally-advanced cancers to shrink tumors before surgery.

Neoadjuvant Hormone Therapy
Hormone therapy used as a first treatment. Often used for large or locally-advanced cancers to shrink tumors before surgery.

Neoadjuvant Therapy (Preoperative Therapy)
Chemotherapy or hormone therapy used as a first treatment. Often used for large or locally-advanced cancers to shrink tumors before surgery.

Abnormal growth.

Excess number of cells in a mass that can be either benign (not cancerous) or malignant (cancerous).

Nested Case-Control Study 
A case-control study done within a prospective cohort study. The major advantage of a nested case-control study over a regular case-control study is the exposure of interest (for example, diet or alcohol use) is measured before any of the participants have disease, making it less subject to bias.

Nipple-Sparing Mastectomy
A breast reconstruction procedure that removes the tumor and margins as well as the fat and other tissue in the breast, but leaves the nipple and areola intact.

Node-Negative (Lymph Node-Negative)
Cancer that has not spread to the lymph nodes. See Lymph Node Status.

Node-Positive (Lymph Node-Positive)
Cancer that has spread to the lymph nodes. See Lymph Node Status.

1. In treatment, describes a procedure that does not penetrate the skin (or any body opening) with a needle or other instrument.

2. In breast cancer pathology, describes a cancer that has not spread beyond the ducts or lobules where it began (see Carcinoma in Situ).

Describes a breast lump or abnormal area that cannot be felt but can be seen on an imaging test (such as a mammogram).

Normal Tissue
Cells that are cancer-free.  

Nuclear Medicine Imaging of the Breast (Molecular Breast Imaging)
A technique under study for use in the early detection of breast cancer. Nuclear medicine imaging uses short-term radioactive agents given through an IV. Cancer cells absorb these agents and can be imaged with a special camera. Nuclear medicine imaging is not a standard breast cancer screening tool. Breast-specific gamma imaging and scintimammography are types of nuclear medicine imaging.

The part a cell that contains the genetic material DNA. Nuclei is the plural of nucleus.

Top of Document  



Observational Study 
A research study where participants live their daily lives as usual and report their activities to researchers.

Odds Ratio 
A measure reported in case-control studies that describes the increase (or decrease) in disease risk related to a risk factor. An odds ratio is interpreted in the same way as a relative risk, though it is calculated differently.

The physician in charge of planning and overseeing cancer treatment.

Surgical removal of the ovaries.

A drug that contains opium or a substance made from opium and is used to treat pain.

A drug that does not contain opium or any substances made from opium, but is used to treat pain.

A condition marked by a loss of bone mass and density that causes bones to become fragile.

Out-of-Network Provider
Any health care provider or medical center (hospital or other treatment center) that is not part of a particular group health plan or health maintenance organization (HMO).  

Overall Survival (Overall Survival Rate, Survival)
The percentage of people alive for a certain period of time after diagnosis with a disease (such as breast cancer) or treatment for a disease.

Top of Document  



Paget Disease of the Breast (Paget Disease of the Nipple)
A rare cancer in the skin of the nipple or in the skin closely surrounding the nipple that is usually, but not always, found with an underlying breast cancer (ductal in situ carcinoma or invasive breast cancer). In these cases, the tumor grows from underneath the nipple and breaks out onto the surface of the nipple.

Palliative Therapy (Palliative Care, Palliation)
Care focused on relieving or preventing symptoms (like pain) rather than treating disease.

Describes a breast lump or abnormal area that can be felt during a clinical breast exam. 

To examine, using the hands and fingers.

PARP (poly(ADP-ribose) polymerase) Inhibitors
A class of targeted therapy drugs that block an enzyme involved in DNA repair (called PARP enzyme).  

Partial Mastectomy (see Lumpectomy

Pathologic Response
A measure describing how much of the tumor is left in the breast and lymph nodes after neoadjuvant (before surgery) therapy. The pathologic response gives some information about prognosis. A complete pathologic response means there is no invasive cancer in the tissue removed during breast surgery.

The physician who uses a microscope to study the breast tissue and lymph nodes removed during biopsy or surgery and determines whether or not the cells contain cancer.

The time in a woman’s life prior to menopause when menstrual periods become irregular and some menopausal symptoms may begin.

Peripherally Inserted Central Catheter (PICC)
A small tube used to deliver medicine to the body through a vein. Instead of being reinserted for each use, a PICC is left in place to allow access for a long period of time (weeks to months).

Permanent Section
A method used in diagnosis. Thin slices of tissue are processed and put on a slide so that a pathologist can study them under a microscope. These sections are of better quality than frozen sections.

A device that uses infrared light beams to measure limb volume. 

Personalized Medicine 
Using information about a person's genes, the tumor’s genes, molecular characteristics of the tumor and the environment to prevent, diagnose and treat disease (such as the use of targeted therapies).   

PET (Positron Emission Tomography)
A procedure where a short-term radioactive sugar is given through an IV so that a scanner can show which parts of the body are consuming more sugar. Cancer cells tend to consume more sugar than normal cells do. PET is sometimes used as part of breast cancer diagnosis or treatment, but is not used for breast cancer screening.

Pharmacogenomics (Pharmacogenetics)
The study of the way genes affect a person’s response to drugs to help predict which drugs may offer him/her the most benefit. 

A characteristic in a person that results from the interaction between his/her genes and his/her environment.

Phyllodes Tumor
A rare sarcoma (cancer of the soft tissue) in the breast.

Pituitary Gland
A part of the brain that controls growth and other glands in the body, such as the ovaries.

An inactive medicine sometime used to have a comparison to a new drug in a clinical study. May be called a "sugar pill."

Pooled Analysis
A method for collecting the individual data from a group of studies, combining them into one large set of data and then analyzing the data as if they came from one big study.  

Positron Emission Tomography (see PET

Postmenopausal Hormone Use (see Menopausal Hormone Therapy)  

Precision Medicine (see Personalized Medicine)

Predictive Factors
Factors (such as hormone receptor status) that help guide treatment for a specific cancer case.

To make more at risk for a disease.

Premenopausal Women
Women who have regular menstrual periods.

Premium (Insurance Premium)
The cost of insurance coverage for a certain period of time.

Preoperative Chemotherapy (see Neoadjuvant Chemotherapy)

Prevalence Rate
The proportion (percentage) of people in a population who have a certain disease, behavior or characteristic at a defined point in time.

Steps taken to lower the risk of a disease.

Primary Chemotherapy (see Neoadjuvant Chemotherapy)

Primary Tumor
The original cancer.

A hormone made by the body that is important in menstrual cycles and pregnancy. May be made in a laboratory (called progestin) and used in birth control pills, menopausal hormone therapy and other types of hormone treatment.

Progesterone Receptor
Specific proteins on cells that progesterone hormones attach to. A high number of progesterone receptors on a breast cancer cell often means the cancer cell needs progesterone to grow.

Any substance (laboratory-made or natural) that has some or all of the effects of progesterone in the body.

The expected or probable outcome or course of a disease (the chance of recovery).

Prognostic Factors
Factors (such as tumor type, size and grade) that help determine prognosis.

The growth or spread of cancer, with or without treatment.

Progression-Free Survival
The length of time a person lives with cancer (such as metastatic breast cancer) before the cancer grows or spreads.

Rapidly growing and increasing in number. 

Prophylactic Mastectomy
Preventive surgery where one or both breasts are removed in order to prevent breast cancer. When both breasts are removed, the procedure is called bilateral prophylactic mastectomy.

Prospective Study
An observational study that follows people forward in time. See Cohort Study

Prosthetic (Breast Prosthetic, Prosthesis)
An artificial breast form that can be worn under clothing after a mastectomy.

An outline or plan for the use of an experimental drug, treatment or procedure in cancer therapy or diagnosis.

Punch Biopsy
Removal of a small circle of skin (with a special instrument called a punch or trephine) to be tested for cancer cells. 

Top of Document  



Surgery where one quadrant or 25 percent of the breast is removed. See Lumpectomy.

Quality of Care
Measures of how well breast cancer is treated and how well a person is cared for during and after treatment.

Quality of Life
A measure of a person’s well-being and his/her overall enjoyment of life.

Categories of an exposure (like body weight or exercise) based on four equal parts of the total number of people in the study.

Categories of an exposure (like body weight or exercise) based on equal parts of the total number of people in the study. When the total number of people is divided into thirds, the categories are called tertiles. When the total number of people is divided into quarters, the categories are called quartiles.

Top of Document  



RAD (dose of radiation)
Short for "radiation absorbed dose." This term describes the amount of radiation absorbed by the tissues. One RAD is equal to one centigray. See Centigray.

Radial Scars (Complex Sclerosing Lesions)
A benign (not cancer) breast condition with a core of connective tissue fibers. Ducts and lobules grow out from this core.  

Radiation Oncologist
A physician specializing in the treatment of cancer using targeted, high energy X-rays. 

Radiation Therapy (Radiotherapy)
Treatment given by a radiation oncologist that uses targeted, high energy X-rays to kill cancer cells. 

Radical Mastectomy (Halsted Radical) 
Surgical removal of the breast, chest muscles and underarm lymph nodes. Used only when the breast tumor has spread to the chest muscles.

Does not allow radiation to pass through. A radio-opaque object will show up on an X-ray.

A physician who reads and interprets X-rays, mammograms and other scans related to diagnosis or follow-up. Radiologists also perform needle biopsy and wire localization procedures.

Radiotherapy (see Radiation Therapy)

A drug first used to treat osteoporosis and now also used to lower the risk of breast cancer in postmenopausal women at high risk.

Randomized Controlled Trials
Studies where researchers change some participants' behavior or provide a certain therapy to see how it affects health. Participants are randomly assigned (as if by coin toss) to either an intervention group (such as one getting a new drug) or a control group (such as one getting standard treatment).

Reconstruction (see Breast Reconstruction  

Recurrence (Relapse)
Return of cancer. Local recurrence is the return of cancer to the same breast or the same side chest wall. Distant recurrence is the return of cancer that has spread to other parts of the body, such as the lungs, liver, bones or brain. See Metastases.

A treatment plan.

Regional Lymph Nodes
In breast cancer, the axillary (in the underarm area) lymph nodes, infraclavicular (under the collarbone) lymph nodes, supraclavicular (above the collarbone) lymph nodes and internal mammary nodes. See Lymph Nodes.

The shrinking of a tumor. 

Relative Risk 
A measure used to describe the increase (or decrease) in risk related to a specific risk factor. A relative risk is the ratio of two absolute risks: the numerator is the absolute risk among those with the risk factor and the denominator is the absolute risk among those without the risk factor. A relative risk that is greater than one shows a factor increases risk. A relative risk that is less than one shows a factor decreases risk. And, a relative risk of one shows the factor neither increases nor decreases risk (this means the factor is not likely related to risk of the disease). 

Relative Survival (Relative Survival Rate)
A measure used to compare the survival of people who have a certain disease with those who do not at a given time after diagnosis or treatment. The relative survival rate shows whether the disease shortens life. If relative survival is 100 percent at five years after treatment, there is no difference in survival between those who have the disease and those who do not five years after treatment.

Retrospective Study
A study where both the exposure (such as alcohol use) and the outcome (such as breast cancer) occur before the start of the study.

Risk (of disease)
Probability (chance) of disease developing in a person during a specified time period.

Risk-Benefit Ratio
The relationship between the possible (or expected) side effects and benefits of a treatment or procedure.

Risk Factor
Any factor—from a lifestyle choice (such as diet) to genetics to an environmental exposure (such as radiation)—that increases or decreases a person's risk of developing a certain disease.

RNA (Ribonucleic Acid)
A molecule made by cells containing genetic information that has been copied from DNA. RNA performs functions related to making proteins.

Top of Document  



A saltwater solution similar to that found in IV fluids. Saline can be used to fill a breast implant.

Scalp Cooling
The use of a cap filled with a chilled substance during chemotherapy. Scalp cooling is under study as a technique for reducing hair loss due to chemotherapy.

The different combinations and timing for chemotherapy and other drugs.

Sclerosing Adenosis
Small, benign (not cancer) breast lumps caused by enlarged lobules. The lumps may be felt and may be painful.  

Scintimammography (see Nuclear Medicine Imaging of the Breast)

A test or procedure used to find cancer or a benign (not cancer) condition in a person who does not have any known problems or symptoms.

Screening Mammogram
A test used to find early signs of breast cancer in a woman who does not have any known breast problems or symptoms. 

Second Primary Tumor
A second breast cancer that develops in a different location from the first. This is different from a local recurrence, which is the return of the first breast cancer.

Selection Criteria
In a summary research table, the specific standards (such as study design and number of participants) a study has to meet to be included.

Selective Estrogen Receptor Modulator (SERM)
A drug that can either block the effects of estrogen or behave like estrogen, depending on the part of the body being treated. Tamoxifen and raloxifene are SERMs.

The proportion (or percentage) of people who truly have the condition of interest who test positive for that condition.

Sentinel Node Biopsy
The surgical removal and testing of the sentinel node(s) (first axillary node(s) in the underarm area filtering lymph fluid from the tumor site) to see if the node(s) contains cancer cells.

Silicone Gel
Medical-grade, solid form of silicone used for breast implants. Silicone implants can mimic the feel of a natural breast better than saline implants.

Simple Mastectomy (see Total Mastectomy)

Skin-Sparing Mastectomy 
A procedure that surgically removes the breast, but keeps intact as much of the skin that surrounds the breast as possible. This skin can then be used in breast reconstruction to cover a tissue flap or an implant instead of having to use skin from other parts of the body. 

Sonogram (see Ultrasound)

The proportion (or percentage) of people who truly do not have the condition of interest who test negative for the condition.

Stage of Cancer (Cancer Stage)
A way to indicate the extent of the cancer within the body. The most widely used staging method for breast cancer is the TNM system, which uses Tumor size, lymph Node status and the absence or presence of Metastases to classify breast cancers.  

Staging (Cancer Staging)
Doing tests to learn the extent of the cancer within the body (the cancer’s stage 0 to IV). Knowing a cancer’s stage helps determine what treatment is needed and how effective this treatment may be in getting rid of the disease and prolonging life. 

Standard Treatment (Standard of Care)
The usual treatment of a disease or condition currently in widespread use and considered to be of proven effectiveness on the basis of scientific evidence and past experience.

Statistical Significance
Describes whether or not the result of a study is likely due to chance. A statistically significant result likely shows a true link between a risk factor and breast cancer.

Stereotactic Needle Biopsy
Core needle biopsy done with the use of stereotactic (three-dimensional) mammography guidance.

Stereotactic Mammography
Three-dimensional mammography used to guide a needle biopsy.

Supraclavicular Lymph Nodes
The lymph nodes above the clavicle (collarbone). See Lymph Nodes.

Physician who performs any surgery, including surgical biopsies and other procedures related to breast cancer.

Surgical Oncologist
A physician specializing in the treatment of cancer using surgical procedures.

Survival (see Overall Survival and Relative Survival)

Survivor (Breast Cancer Survivor)
A person living with breast cancer (from the time of diagnosis).

The emotional and physical health, life and care of a breast cancer survivor from the time of diagnosis until the end of life.

Systemic (Adjuvant) Treatment
Treatment given in addition to surgery and radiation to treat breast cancer that may have spread to other parts of the body. It may include chemotherapy, targeted therapy and/or hormone therapy.

Top of Document  



Tamoxifen (Nolvadex)
A hormone therapy drug (taken in pill form) used to treat early and advanced stage breast cancers that are hormone receptor-positive. These breast cancers need estrogen to grow. Tamoxifen stops or slows the growth of these tumors by blocking estrogen from attaching to hormone receptor in the cancer cells. 

Targeted Therapy 
Drug therapies designed to attack specific molecular agents or pathways involved in the development of cancer. Trastuzumab (Herceptin) is an example of a targeted therapy used to treat breast cancer. 

Categories of an exposure (like body weight or exercise) based on three equal parts of the total number of people in the study.

Therapeutic Touch
An integrative or complementary therapy where trained practitioners enter a semi-meditative state and hold their hands just above a person’s body to sense energy imbalances due to illness. Healing energy is then said to transfer to the person.

An imaging technique that uses infrared light to measure temperature differences on the surface of the breast. The U.S. Food and Drug Administration (FDA) and the American College of Radiology do not view thermography as a valuable breast cancer screening method.

A group or layer of cells.

Tomosynthesis (see Breast Tomosynthesis) 

Total Mastectomy (Simple Mastectomy) 
Surgical removal of the breast but no other tissue or nodes. Used for the treatment of ductal carcinoma in situ and, in some cases, breast cancer recurrence. Also used in prophylactic mastectomy. 

Trastuzumab (Herceptin)
A drug that is a specially made antibody that targets cancer cells with a lot of the protein called HER2/neu on their surfaces. When attached to the HER2/neu protein, trastuzumab slows or stops the growth of the cancer cells. Trastuzumab is used to treat HER2/neu-positive breast cancer. Herceptin is the brand name for trastuzumab.

Triple Negative Breast Cancer
A breast cancer that is estrogen receptor-negative, progesterone receptor-negative and HER2/neu-negative. These factors limit treatment choices. Most triple negative tumors are basal-like tumors. These breast cancers tend to be aggressive and are more common in African American women.

An abnormal growth or mass of tissue that may be benign (not cancerous) or malignant (cancerous). 

Tumor Grade
Describes how closely cancer cells look like normal cells. Grade 1 tumors have cells that are slow-growing and look the most like normal cells. Grade 3 tumors have cells that are fast-growing and look very abnormal. Grade 2 tumors fall in between grade 1 and grade 3. 

Tumor Marker
A substance found in blood that may be a sign of metastatic breast cancer. Tumor markers are found in both normal cells and cancer cells, but they are made in larger amounts by cancer cells. A tumor marker may help indicate metastatic breast cancer treatment activity. The term tumor marker may also be used more broadly to refer to characteristics of tumor cells such as hormone receptors.  

Tumor Profiling (Gene Expression Profiling)
Tests that give information about thousands of genes in cancer cells. Specific genes (or combinations of genes) may give information useful in prognosis and in making treatment decisions.  

Two-Step Procedure
Biopsy and further surgical treatment done at two separate times.

Tyrosine-Kinase Inhibitors
A class of drugs that target enzymes important for cell functions (called tyrosine-kinase enzymes). These drugs can block tyrosine-kinase enzymes at many points along the cancer growth pathway.  

Top of Document  



Ultrasound (Sonogram)
Diagnostic test that uses sound waves to make images of tissues and organs. Tissues of different densities reflect sound waves differently.

Usual Hyperplasia
A benign (not cancer) breast condition where breast cells are growing rapidly (proliferating). The proliferating cells look normal under a microscope. Although usual hyperplasia is not breast cancer, it increases the risk of breast cancer. 

Top of Document  



Vaginal Atrophy (Atrophic Vaginitis)
Vaginal dryness. 

Top of Document  



Wire Localization (Needle Localization)
Insertion of a very thin wire into the breast to highlight the location of an abnormal area so that it can be removed during biopsy or lumpectomy.

Top of Document  


Radiation that, at low levels, can be used to make images of the inside of the body. For example, a mammogram is an X-ray image of the breast. At high levels of radiation, X-rays can be used in cancer treatment.

Top of Document 


*Parts of this glossary were adapted from the National Cancer Institute's Dictionary of Cancer Terms and the American Cancer Society’s Cancer Glossary.

**Glossary terms relating to radiation therapy adapted from the Joint Center for Radiation Therapy’s Glossary of Terms

Updated 05/02/14