Cancer is a disease in which cells become abnormal and form more cells in an uncontrolled way. With breast cancer, the cancer begins in cells that make up the breasts — usually in the tubes that carry milk to the nipple or the glands that make milk. The cancerous cells form a mass of tissue called a tumor. Sometimes, the cancer spreads to other parts of the body.

Resources and Links

For more information about breast cancer, call at 800-994-9662 (TDD: 888-220-5446) or contact the following organizations:

American Cancer Society
Phone: 800-227-2345
National Breast and Cervical Cancer Early Detection Program
Phone: 800-232-4636
National Cancer Institute, NIH, HHS
Phone: 800-422-6237
Susan G. Komen for the Cure
Phone: 877-465-6636
Y-ME National Breast Cancer Organization
Phone: 800-221-2141


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Other than skin cancer, breast cancer is the most common cancer in American women. It also is the second-leading cancer killer of women, after lung cancer. Every woman has a chance of getting breast cancer. About 1 in 8 women will find out she has breast cancer at some point in her life. This might sound scary. But today, most women with breast cancer survive it. With breast cancer screening, including mammograms, doctors often can find cancer early. Treatment has the best chance of success  when cancer is found early.

What is breast cancer?
Breast basics

A woman’s breast is made of glandular tissue, connective tissue, fatty tissue, blood vessels, lymph tissue, and nerves. Each breast contains up to 20 sections of glandular tissue called lobes. Each lobe has many smaller sections called lobules, where milk is made. Milk flows from the lobules through thin tubes called ducts to the nipple. The nipple is the small, raised area at the tip of the breast. The areola is the area of darker-colored skin around the nipple.


Each breast also contains lymph vessels. These are thin tubes that carry lymph to small, bean-shaped glands called lymph nodes. Lymph nodes are found near the breast, under the arm, and throughout the body. Lymph nodes and lymph vessels are part of the lymph system, which helps your body fight disease and infection. The chest muscle and chest wall are behind the breasts.

image credit: National Cancer Institute

The breast and nearby lymph nodes. Image credit: National Cancer Institute

Breast cancer
Cancer is a disease in which cells become abnormal and form more cells in an uncontrolled way. With breast cancer, the cancer begins in the tissues that make up the breasts. The cancer cells may form a mass called a tumor. (Note: Not all tumors are cancer.) They may also invade nearby tissue and spread to lymph nodes and other parts of the body. The most common types of breast cancer are:

  • Ductal carcinoma – Cancer that begins in the ducts and grows into surrounding tissues. About 8 in 10 breast cancers are this type.
  • Lobular carcinoma (LAH-byuh-luhr KAR-sih-NOH-muh) – Cancer that begins in lobules and grows into surrounding tissues. About 1 in 10 breast cancers are this type.
    With routine screening, breast cancer often can be found at an early stage, before the cancer has spread.
Breast cancer symptoms
Thanks to screening, breast cancer often is found before a woman has any physical symptoms. Yet a woman should know how her breasts normally look and feel so that she can report any unusual changes to her doctor. Reasons to call your doctor include:

  • A lump in or near your breast or under your arm
  • Thick or firm tissue in or near your breast or under your arm
  • A change in the size or shape of your breast
  • Nipple discharge (fluid that is not breast milk)
  • Nipple changes, such as a nipple that turns inward (inverted) into the breast
  • Changes to your breast skin, areola, or nipple, such as itching, redness, scaling, dimpling, or puckering

Keep in mind that most breast changes are not cancer. For instance, nipple discharge can be caused by birth control pills, some medicines, and infections. Or, a breast lump could be a cyst, which is a fluid-filled lump that is not cancer. Early breast cancer usually does not cause pain. Still, if you notice a change in your breast or pain, call your doctor and schedule a visit. Don’t wait until your next checkup.

Breast cancer risk factors and prevention
“What’s my risk of breast cancer?” is a question many women ask their doctors. Doctors have tools to help estimate a woman’s personal risk. Most women who get breast cancer have no known risk factors besides age. Many women with one or more risk factors never get breast cancer. So it’s impossible to know who will actually get breast cancer.

Factors that affect a woman’s risk of breast cancer include:

  • Age. The strongest risk factor is age. Risk goes up as a woman gets older. Most women who get breast cancer are older than 50.
  • Personal history of breast cancer. Women who have had breast cancer in one breast are more likely to get it in the other breast.
  • Family history. Having a mother, sister, or daughter who has had breast cancer increases a woman’s risk. The risk is higher if her family member got breast cancer before age 40. A woman’s risk also is increased if more than one family member on either her mother’s or father’s side of the family has had breast cancer.
  • Inheriting certain harmful gene mutations. Here are some key points about genes and breast cancer:
    Inheriting changes to certain genes, such as BRCA1 and BRCA2, greatly increases the risk of breast cancer.Inherited genetic changes account for about 10 percent of all breast cancers.If you have a relative who has a harmful gene mutation, you may want to talk to a genetic counselor to learn more about your personal risk. You may also want to seek genetic counseling if your family history of cancer suggests a gene mutation.A woman known to carry a harmful gene mutation should talk to her doctor about ways to try to lower her breast cancer risk or find breast cancer early.
  • Certain breast changes that are not cancer. Women who have certain types of abnormal breast changes, such as atypical hyperplasia, ductal carcinoma in situ, and lobular carcinoma in situ, have a higher risk. These changes are found during a breast biopsy.
  • Breast tissue that is dense on mammogram. Women whose breasts have more dense tissue relative to fatty tissue have a higher risk than women of about the same age who have little or no dense breast tissue.
  • Menstrual and reproductive history. Getting your first menstrual period before age 12 increases breast cancer risk. Reaching menopause after age 55 increases breast cancer risk. Never having children or having children after age 30 also increases risk. Women who have a first baby before age 20 have a lower risk.
  • Taking the hormones estrogen and progestin. Using menopausal hormone therapy containing both estrogen and progestin for more than five years increases breast cancer risk. It’s not clear whether estrogen-only therapy affects risk. Using birth control pills may slightly increase the risk of breast cancer in current users, but this risk returns to normal over time.
  • Radiation therapy to the chest. Radiation therapy to the chest for the treatment of cancer increases breast cancer risk. Risk depends on the dose of radiation and age of treatment. The risk is highest for radiation treatment used during puberty.
  • Body weight. The chance of getting breast cancer after menopause is higher in women who are overweight or obese.
  • Drinking alcohol. The more alcohol a woman drinks, the greater her risk of breast cancer.
  • Taking DES. The drug DES, or diethylstilbestrol (dye-ETH-uhl-stil-BES-trol), was given to some pregnant women in the United States between about 1940 and 1971 to prevent miscarriage. (It is no longer given to pregnant women.) Women who took DES during pregnancy may have a slightly increased risk of breast cancer.
  • Physical activity. Women who are not physically active throughout life may have an increased risk of breast cancer. Strenuous exercise for more than four hours per week may help lower breast cancer risk. Also, being active can help women prevent overweight and obesity, which are known risk factors for breast cancer in women who have reached menopause.
  • Breastfeeding. Women who breastfeed have a lower risk of breast cancer.
  • Race. In the United States, white women have the highest breast cancer rates. Yet women of all races get breast cancer. African-American women are more likely to die from breast cancer than white women. One reason is that cancer is often found in African-American women at a later, more advanced stage, when it may be harder to treat.

Researchers continue to look for other factors that might affect a woman’s risk of getting breast cancer. Factors that do not appear to affect a woman’s breast cancer risk include:

  • Breast implants
  • Miscarriage or abortion
  • Underarm deodorant and antiperspirants
  • Smoking – Although neither smoking nor secondhand smoke has been shown to increase the risk of breast cancer, they do have other cancer-causing effects.
  • Smoking is the number one risk factor for lung cancer.

If you’re looking for ways to lower your breast cancer risk, focus your efforts on a healthy lifestyle. Wholesome and well-balanced meals and regular physical activity can help you to maintain a healthy weight. Limit alcohol to no more than one drink a day. Whether these steps will protect you from breast cancer is not certain. But living a healthy lifestyle is a cornerstone of disease prevention.

Screening and diagnosis: Mammogram, clinical breast exam, and other tests

Breast cancer screening looks for signs of cancer before a woman has symptoms. Screening can help find breast cancer early, when the chance of successful treatment is best. Two tests are commonly used to screen for breast cancer:

  • Mammogram. A low-dose x-ray exam of the breasts to look for changes that are not normal. Check the screening charts (PDF, 132KB) to see when you should get a mammogram.
  • Clinical breast exam (CBE). The doctor looks at and feels the breasts and under the arms for lumps or anything else that seems unusual. Ask your doctor if you need a CBE.

Regular screening is the best way to find breast cancer early in most women. If you are at higher risk of breast cancer, your doctor might want to use other tests too, such as a different type of mammogram or magnetic resonance imaging (MRI).

It is important to let your doctor know if you find any changes in your breast, such as a lump or dimpling or puckering of the skin. Although research results do not support an official recommendation that all women conduct breast self-exams, knowing your body is key to pointing out any concerns to your doctor.

Diagnosing breast cancer

Screening tests look for signs of cancer. If a screening mammogram or CBE shows a breast change that could be cancer, additional tests are needed to learn more. These tests might include:

  • Diagnostic mammogram. This type of mammogram uses x-rays to take more detailed images of areas that look abnormal on a screening mammogram.
  • Ultrasound exam. Sound waves help your doctor see if a lump is solid (could be cancer) or filled with fluid (a fluid-filled sac that is not cancer).
  • Magnetic resonance imaging (MRI). Radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the breast. MRI may be used if enlarged lymph nodes or lumps are found during a clinical breast exam that are not seen on a mammogram or ultrasound.
  • Breast biopsy. Fluid or tissue is removed from the breast and checked for cancer cells. There are many types of biopsy. A biopsy is the only test to find out if cells are cancer.

Not all women who have abnormal screening test results need to have a biopsy. Sometimes, doctors can rule out cancer based on the results of follow-up tests without biopsy.

Finding out about “abnormal” breast changes can be scary. Talk to your doctor about what tests you might need and what the test results mean. If you learn that you have cancer, your doctor will help you move forward and begin treatment.

Related information

Some women have not gotten regular mammograms in the past because of cost and lack of insurance. But insurance companies are now required to cover mammograms every 1 to 2 years for women over 40 at no cost to the patient because of the Affordable Care Act.

Depending on factors such as family history and your general health, your doctor may recommend a mammogram before age 40 or more often. Learn more about mammograms and what to expect.

Mammograms fact sheet
Screening tests and vaccines
Steps to breast self-exam (from Susan G. Komen for the Cure)

Breast cancer treatment

Breast cancer treatment often involves more than one approach. The treatment plan your doctor suggests will be based on several factors, such as:

  • The stage of the cancer
  • The size of the tumor compared to the size of your breast
  • The type of breast cancer you have
  • Whether you have reached menopause
  • Your general health
  • Don’t be afraid to ask your doctor lots of questions or to meet with other doctors. The better you understand your options, the easier it will be for you to make an informed choice about treatment.


After breast cancer is found, your doctor will need to learn the extent of the cancer. This is called staging. The stage is based on:

The tumor size
Whether the cancer has spread to nearby tissue
Whether the cancer has spread to nearby lymph nodes or other parts of the body
Many tests may be used to learn this information. A woman’s treatment options depend greatly on the cancer stage. Often, the stage is not known until after a woman has surgery to remove the cancer from her breast.

Types of treatment

Women with breast cancer may have one or more of these treatments:

  • Surgery – Surgery is the most common treatment for breast cancer. The goal of surgery is to remove all the cancer from the breast. Many women are able to have surgery that removes the cancer but leaves the breast intact. Other women may have their entire breast removed. Plastic surgery to rebuild the breast, called breast
  • reconstruction, often can be done at the same time as breast cancer surgery. Women who are thinking about breast reconstruction should talk to a plastic surgeon before having cancer surgery.
  • Radiation therapy – High-energy x-rays or other types of radiation are used to kill cancer cells or keep them from growing.
  • Chemotherapy – Drugs are used to kill cancer cells or keep them from dividing.
  • Hormone therapy – The hormone estrogen causes some types of breast cancer to grow. Hormone therapy reduces the body’s ability to make hormones or stops their action to keep cancer from growing.
  • Targeted therapy – Drugs or other substances are used to find and attack specific cancer cells without harming normal cells.
    For many women, breast cancer does not come back after treatment. For some women, breast cancer comes back after a period of time when it could not be detected. This is called recurrent breast cancer. It may return close to the location of the original tumor or in another part of the body. Treatment options depend on where the cancer returned.

New cancer treatments are being studied. Some women with breast cancer may be able to benefit from new cancer treatments by taking part in clinical trials. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment. Learn about clinical trials for women with breast cancer.

Help and support

If you just found out you have breast cancer, you are likely to feel afraid and overwhelmed. You might be worried about your family, your job, and the unknown. The waiting between doctor visits might seem endless. Or things might be happening so quickly that you feel like you have no control. Even though you have a lot to think about and big decisions to make, you may feel stuck, unsure how to take the next step.

Take heart — information about breast cancer, its treatment, and breast reconstruction is plentiful. Turn to resources you can trust. To learn more about breast cancer and its treatment, you also can speak with a National Cancer Institute Information Specialist via a live online text chat or by calling 800-4-CANCER (800-422-6237).

Whatever you do, make sure to take good care of yourself before, during, and after treatment. Eat healthy foods and stay as active as you can. Also, don’t take on breast cancer alone. Turn to loved ones and friends for support. Think about joining a support group for women with breast cancer. Women in treatment and breast cancer survivors can be an amazing source of strength during and after your treatment.

More information on Breast cancer treatment
Read more from

  • Breast Cancer Fact Sheet – This fact sheet provides information on why women should be concerned about breast cancer and gives resources for more information.
  • Early-stage Breast Cancer Treatment Fact Sheet – This fact sheet addresses questions that women commonly have about breast cancer and its treatment. It explains the two surgical options used to treat early-stage breast cancer and lists resources for patients seeking more information.

Explore other publications and websites

  • Breast Cancer Prostheses and Hair Loss Accessories List (Copyright © American Cancer Society) – This site lists producers of breast prostheses and accessory items.
  • Breast Cancer: A Resource Guide for Minority Women – This publication lists organizations, documents, journal articles, and other resources to help minority women affected by breast cancer.
  • Breast Reconstruction After Mastectomy (Copyright © American Cancer Society) – This publication gives women the facts about breast reconstruction. Please remember that the decision to have breast reconstruction is a matter of individual choice. No one source of information can provide every fact or give all the answers. Therefore, you and those close to you should also discuss any questions and concerns with your doctor.
  • BreastCancer101: Basics for the Newly Diagnosed 10 Year Planner (Copyright © CANCER101) – If you have breast cancer or know someone who does, this organizer will help empower a person to take control of a breast cancer diagnosis.
  • Coping With Cancer: Tools to Help You Live (Copyright © CancerCare) – This booklet discusses living with cancer, learning about your diagnosis and treatment, finding financial help, and coping with the emotional aspects of cancer.
  • Financial Assistance and Other Resources for People With Cancer – This Internet site provides links to financial information, legal information, and insurance information for people who have cancer.
  • I Still Buy Green Bananas: Living With Hope, Living With Advanced Breast Cancer (Copyright © Breast Cancer Network of Strength) – The booklet is for women with advanced breast cancer. It discusses the common fears and emotions that women with breast cancer face and gives pointers to try to help women cope with cancer.
  • Lumpectomy (Copyright © – Lumpectomy is surgery in which the tumor and some surrounding tissue are removed. This publication explains how the surgery is done and the risks and gives questions for you to ask your doctor.
  • Mastectomy (Copyright © – This publication explains what a mastectomy is, why you would need one, and the different types of mastectomies.
  • Mastectomy vs. Lumpectomy (Copyright © – This publication discusses the difference between mastectomy and lumpectomy, as well as the advantages and disadvantages of both procedures.
  • What Happens After Treatment for Breast Cancer? (Copyright © American Cancer Society) – This publication provides guidance on life after breast cancer treatment. It discusses physical symptoms you may experience after treatment, such as lymphedema, and other life issues you may encounter, including adjustments of body image, quality of life, and sexuality.
  • What You Need to Know About Breast Cancer – This information summary is designed for women who have been diagnosed with breast cancer and who are about to undergo treatment.

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