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Breast Screening Decisions is a website to help you make informed, personalized decisions about when to start and how often to have screening mammograms.

Breast Cancer

Breast cancer is a disease in which cancer cells begin growing in the breast. These cancer cells may line the breast ducts or lobules without invading the surrounding tissues (carcinoma in situ) or invade surrounding tissue (invasive cancer). When the cancer spreads beyond the breast it is called metastatic cancer.

Although most often diagnosed in women, men can also be diagnosed with breast cancer.

For more information about this topic, click on the link below.
National Cancer Institute - What is Breast cancer?

Signs & Symptoms

Breast cancer symptoms vary from woman to woman, and most women experience no symptoms. Breast cancer symptoms may include:

  • A lump or thickening in the breast
  • Clear or bloody nipple discharge
  • Breast skin dimpling
  • A newly inverted nipple
  • Redness and thickening of the skin over the breast
  • Peeling, flaking or crusting of the nipple
  • Swelling or lump in the armpit
  • Breast pain

Most of the time these symptoms are not breast cancer, but it's important to see your doctor to be sure.

Risk Factors

The exact cause of breast cancer is not known, but certain factors may increase a woman's risk of developing breast cancer. How these risk factors lead to breast cancer is not entirely understood, although genetic and hormonal mechanisms appear to be important.

  • Increasing age: The chance of being diagnosed with breast cancer is:
    • From ages 40-49: 1 in 69
    • From ages 50-59: 1 in 42
    • From ages 60-69: 1 in 29
  • A family history of breast cancer: Both your mother's and father's family history are important. Having one first-degree relative (mother, father, sister, daughter) doubles the risk of developing breast cancer; two first-degree relatives increases the risk three-fold. The risk is highest if the family member had breast cancer before age 50.
  • Certain breast conditions detected by breast biopsy:
    • DCIS (ductal carcinoma in situ), LCIS (lobular carcinoma in situ) or ADH (atypical ductal hyperplasia) detected by a breast biopsy can increase breast cancer risk as much as 4-5 fold. Women with one of these conditions may be treated with surgery, radiation, or hormonal therapy in order to decrease their risk of developing invasive breast cancer.
    • Radial scarring, papillomatosis, or sclerosing adenosis can increase breast cancer risk slightly.
    • Other common breast conditions such as fibroadenomas and benign papillomas do not increase breast cancer risk.
  • Genetic mutations: About 5-10% of breast cancers are thought to result from genetic mutations passed down from parent to child. The most common mutations are in genes knows as BRCA1 and BRCA2. Other genetic mutations have also been identified. Genetic counseling and testing are available to women with family histories that suggest a possible gene mutation.
  • History of chest radiation prior to age 40: Women who have had radiation to the chest to treat another condition, such as Hodgkin's disease, lymphoma or thyroid cancer, have an increased risk of breast cancer.
  • Reproductive and menstrual history: Being over age 35 at the time your first child is born; never having had children; having your first menstrual period before age 12; and having menopause after age 55 all increase a woman's risk of developing breast cancer. These factors increase risk only very slightly, however. The risk is probably related to exposure of the breast to reproductive hormones.
  • DES exposure: Women whose mothers took diethylstilbestrol (DES), a hormone to prevent miscarriage, while they were pregnant with them are at a slightly higher risk for breast cancer. DES has not been allowed for use in pregnant women since 1971.
  • Postmenopausal hormone replacement therapy: Women who use estrogen and progesterone hormone therapy in menopause have a slightly higher risk of breast cancer. Women who use estrogen alone may not have an increased risk of breast cancer, although some studies suggest there is a risk with long-term use of estrogen.
    • Medications to prevent breast cancer: In women at high risk for breast cancer, there are hormonal treatments (tamoxifen and raloxifene) that can significantly reduce the risk of breast cancer. These medications have not been shown to prevent deaths from breast cancer. They also have side effects, which must be balanced against their potential benefits. These medications are not appropriate for use in women at low to average risk of developing breast cancer.
  • Very dense breasts: Women with very dense breasts have elevated risk of developing breast cancer. Breast density may be a marker for increased hormone exposure, and may also limit the ability of mammograms to detect breast cancers.
  • Other factors: Other factors that may contribute to breast cancer risk: drinking more than one alcoholic drink daily; being obese or inactive. These factors have only a small impact on your risk.
For more information about this topic, click on the link below.
National Cancer Institute - What is Breast cancer?

Decreasing Your Breast Cancer Risk

While we do not know for certain what causes breast cancer, things you can do that may lower your risk of developing breast cancer.

  • Breast feeding: Breast feeding may decrease breast cancer risk slightly, perhaps because it lowers estrogen levels and decreases the number of menstrual periods a woman has in her lifetime.
  • Limiting alcohol consumption: Whether it is beer, wine or liquor, drinking alcohol increases a woman's risk of developing breast cancer. It has been recommended that women consume no more than one drink of alcohol per day.
  • Maintaining a healthy weight: Research suggests a link between being overweight and an increased risk of breast cancer, particularly if the weight gain occurs later in life and after menopause.
  • Engaging in physical activity: Being active helps to control weight, and thus may help reduce breast cancer risk.
  • Limiting menopausal hormone use: While hormone replacement therapy (HRT) is an extremely effective treatment for the symptoms of menopause, it can cause a small increase in breast cancer risk. Experts recommend using HRT at the lowest effective dose for the shortest possible time to treat menopausal symptoms.

Much remains unknown, but it has been estimated that as many as a third of breast cancers might be prevented if all women maintained a healthy weight, did not smoke or drink alcohol, and did not use hormone replacement. While there is no guarantee that doing these things will protect you from breast cancer, they may also have a positive impact on your health in general.

Race/Ethnicity And Breast Cancer

Rates of developing breast cancer are slightly different for women of different races and ethnic groups. White women are slightly more likely to develop breast cancer than African American, Hispanic, and Asian women. However, African American/black women are more likely to develop more aggressive breast cancer, and in African American/black women breast cancer may be diagnosed at a more advanced stage. African American/black women are also more likely to die of breast cancer than women of other racial and ethnic groups. Some of these differences between women of different races/ethnicities may be due to differences in their access to medical care, including screening mammography.

For more information about this topic, click on the link below.
National Cancer Institute Disparities Fact Sheet - Race/Ethnicity

Screening Mammography

A screening mammogram is an x-ray to look for breast cancer in a healthy woman who has no signs or symptoms of breast cancer. Usually the technician takes 4 images or views or each breast. The mammogram may be read then or at a later time by a radiologist. These images may be digital or standard x-ray films.

The purpose of a screening mammogram is to detect breast cancer before it is large enough to be felt or cause symptoms. Screening mammograms do not prevent breast cancer.

For more information about this topic, click on the link below.
Women's - Mammogram Fact Sheet
CDC - Understanding Mammograms

Diagnostic Mammography

A diagnostic mammogram is an x-ray of the breast performed in a woman who feels a lump or has other breast symptoms. Diagnostic mammograms are also done when a screening mammogram shows an abnormality that needs further evaluation. Additional x-rays of the area of concern in the breast are obtained. The radiologist may also perform a physical breast exam or take additional images using ultrasound.

For more information about this topic, click on the links below.
Women's - Mammogram Fact Sheet
CDC - Understanding Mammograms

Digital vs. Film Mammograms

Mammogram x-rays can be stored on film or as digital images in a computer. Unlike film images, digital images can be manipulated - darkened, lightened, enhanced or magnified. Digital images can also be shared easily with other radiologists or health care providers.

Overall, there is no difference in cancer detection between film and digital mammograms. However, in women who are under age 50 or those over age 50 who are still menstruating or within a year of menopause, digital mammograms may be better than standard film mammograms for detecting breast cancers. It is not known whether this difference in cancer detection with digital mammograms results in improved cancer survival.

For more information about this topic, click on the links below.
NCI - Mammograms - Types of Mammograms

Benefits and Potential Harms of Screening Mammography

When making the decision to have a mammogram or not, it is important to consider both the benefits and the potential risks of screening.

  • Mammograms can reduce the number of deaths from breast cancer
    By detecting breast cancer at an early stage, mammograms allow for early treatment that can increase the chance of a cure, thus reducing the chance of dying from breast cancer. Mammograms do not prevent most breast cancer deaths. Some fast-growing or aggressive breast cancers may have already spread to other parts of the body by the time they are detectable by mammography. Some breast cancers spread so slowly that finding them early with mammography doesn't make a difference, because they have such a small chance of causing death in the first place.
  • Mammograms are not perfect
    Some breast cancers will be missed by mammography - about 20% are just not visible. These are called false negatives. False-negative mammograms are more common in women under age 50 because their breasts are dense, which can make finding cancer more difficult.

    Most abnormal mammograms are not cancer - these are called false positives. The chance of a false-positive mammogram is about 10% at any given mammogram. Slightly more than half of all women getting screening mammograms for a 10-year period will at some point have a false-positive result, and 7-9% will have an unnecessary biopsy.

    Having films available from previous mammograms for comparison can reduce the chance of a false-positive mammogram. If you go to a new mammogram screening facility, you should arrange to bring copies of your previous mammogram films.

  • Mammograms can lead to over-diagnosis and over-treatment
    Some cancers detected by mammograms may never cause symptoms or lead to death. This is especially the case with DCIS or ductal carcinoma in situ - a non-cancerous breast condition that may develop into breast cancer over time. Because we cannot determine which cancers or DCIS might lead to death, all of them are treated. This may lead to harms from treatment (surgery, radiation, chemotherapy, hormonal therapy) that is ultimately not necessary to save a woman's life.
  • Mammograms are radiation
    The chance of a mammogram actually increasing breast cancer risk due to radiation exposure is extremely low, and is not a cause of concern in routine screening. However, exposure of the developing breast to radiation is a concern, and this is one of the reasons we do not recommend routine screening mammograms in women under age 40, in addition to the fact that cancers are rare in this age group. Cumulative radiation exposure may also be a consideration in high-risk women who start screening early and have repeated mammograms over many years.
For more information about this topic, click on the links below.
Mammogram basics
Radiation Exposure from Mammography

Breast Implants and Mammography

For women with breast implants, mammograms are also an effective screening method for breast cancer. The implant does have the potential to hide breast tissue, making it more difficult to detect breast cancer. For that reason, it is important that women who have breast implants have their mammograms performed at facilities with experience in screening women with implants.

An Abnormal Mammogram

Most of the time, an abnormal mammogram does not mean breast cancer. Any suspicious finding will be called "abnormal" and will likely require further testing. Often these abnormalities are due to benign calcium deposits and non-cancerous cysts or tumors that will be confirmed non-threatening after a diagnostic mammogram, but might require additional monitoring. If the radiologist does suspect breast cancer, a biopsy will be performed where cells of the suspicious tissue are collected and tested for cancer.

For more information about this topic, click on the links below.
Komen - Mammogram Follow up
National Cancer Society - Mammogram Reports

Mammography Cost

The cost of screening mammography varies by State, by facility and by insurance policy. If you have health insurance, you probably have coverage for part or all of the cost of screening. To learn more about the specifics of your plan, contact your health insurance provider directly. If you don't have insurance or have concerns about financial coverage, you may be eligible for free or low-cost screening through a special program in the state where you live.

Myths About Breast Cancer

  • Mammograms prevent breast cancer: FALSE
    Mammograms reduce deaths from breast cancer by detecting cancers before they cause symptoms.
  • Breast injury can cause breast cancer: FALSE
    Bumping, bruising, cutting or otherwise injuring the breast is not a risk factor for getting breast cancer in the future.
  • Monthly breast self exams saves lives: FALSE
    Doing a breast self exam every month has not been shown to reduce deaths from breast cancer. Instead, women are encouraged to practice breast awareness. Be aware of what is normal for you, and see your health care provider if you notice any changes or breast symptoms during your usual activities.
  • Mammograms detect 100% of breast cancers: FALSE
    Mammograms will miss about 10% of breast cancers. If you have a breast lump or other breast symptoms that have not been evaluated, see your doctor immediately, even if you have recently had a normal mammogram.
  • Antiperspirants, deodorants and underarm shaving cause breast cancer: FALSE
    There is very little reliable scientific evidence in humans that antiperspirants, deodorants or underarm shaving cause breast cancer. On the contrary, large studies have found no link.
  • Having a family history of breast cancer means you will get it too: FALSE
    Only about 10% of all breast cancers happen in women who have a family history. The other 90% happen in women with no family history. Just because your mother or sister or other relative had breast cancer it does not mean that you will get it.

    Family histories that suggest a genetic predisposition to breast cancer include breast cancer in multiple family members, cancers diagnosed before age 50, breast cancer in male relatives, and families with breast, ovarian and pancreatic cancer. If you are concerned about your family history, you can see a genetic counselor to discuss your family health history and your screening options. For more information about this topic, click on the link below.
    NCI - Genetic Testing: What you need to know

Other Screening Modalities

Mammography is the only type of breast cancer screening that has been shown to reduce deaths from breast cancer, and mammography is the only type of breast cancer screening that is recommended for women at low to average risk of developing breast cancer. Other types of screening may be used for women at higher-than-average risk.

  • Breast ultrasound:
    Ultrasound uses sound waves to visualize the breast tissue. Alone, ultrasound images, also known as sonograms, are not effective tools for routine breast cancer screening due to high rates of both false-negative and false-positive results. However, sonograms are useful in evaluating abnormalities found on screening mammography, and to visualize cysts and other benign masses in the breast. Sonograms are also used to evaluate breast symptoms and masses in younger women, whose breast density may limit visibility on mammography.

    Women who are at increased risk for breast cancer and also have dense breasts may benefit from adding ultrasound to their mammogram in routine screening.

  • Breast MRI:
    MRI uses magnetic fields to visualize the breast. MRI alone is not a useful tool for routine breast cancer screening due to a high rate of false-positive results. [It also takes longer to perform and is more uncomfortable than mammography.

    In women with a strong family history or who carry a genetic mutation that places them at high risk for breast cancer, MRI is often recommended to be used along with mammography for breast cancer screening.

  • Thermography:
    This experimental technique is not effective as a breast cancer screening tool. It has a very high rate of false-positive results, and cannot detect abnormalities deep within the breast.
  • Breast Tomosynthesis (3-D Mammography):

    Digital breast tomosynthesis is a new technology that allows "three-dimensional" imaging of the breast.

    Several studies have found that, compared with conventional mammography, tomosynthesis reduces the chance that a woman will need to come back for additional breast imaging after a routine screening. Some studies have also found that tomosynthesis is better at detecting invasive cancers than conventional mammography. This would mean that 3-D mammograms are more precise and may be more sensitive than conventional mammograms.

    The benefits of tomosynthesis appear to be greatest in younger women with dense breasts. Conventional mammograms are generally less sensitive in these women, who are also more likely to be called back for additional breast imaging after routine screening.

    Some studies have suggested that tomosynthesis alone could be a substitute for the combination of conventional screening mammogram and breast sonogram (also known as breast ultrasound) that many doctors currently recommend for women at increased risk of developing breast cancer.

    Depending on the equipment and protocols used, digital breast tomosynthesis may or may not expose the breast to more radiation than conventional mammograms. Different mammogram centers use different machines and different image processing, both of which can impact radiation exposure. The amount of radiation delivered during any mammogram also depends on the density and overall thickness of the breast.

    Performing 3D mammograms requires dedicated equipment, expertise and advanced training that not all mammogram centers have.

    We do not know yet if use of 3D mammography for breast cancer screening will lead to lower rates of death due to breast cancer.

  • Nuclear Mammography:
    Nuclear mammography is currently being studied for possible use in breast cancer screening. It is not recommended at this time for routine breast cancer screening.
For more information about this topic, click on the link below.
Komen Foundation - Recommendations for women at higher risk

Medications To Prevent Breast Cancer

Women at increased risk of developing breast cancer based on their personal or family history can consider taking a medication to lower their risk. All of the medications listed below reduce the risk of getting breast cancer, but none has yet been shown to improved breast cancer survival.

  • Tamoxifen: Reduces the risk of both invasive and non-invasive breast cancer in women age 35 and older who are at increased risk of developing breast cancer based on their personal risk factors. Side effects may include hot flashes and vaginal discharge. In pre-menopausal women, it can cause irregular bleeding. Risks may include blood clots in the legs or lungs, cataract formation and a small risk of endometrial cancer. In general, the benefits of tamoxifen outweigh the risks in younger women who are not at increased risk for blood clots or stroke, especially if they have had a hysterectomy.
  • Raloxifene (Evista): Reduces the risk of invasive breast cancer in post-menopausal women who are at increased risk of developing breast cancer based on their personal risk factors. Side effects may include hot flashes, leg cramping, swelling in the hands and feet, joint pain, trouble sleeping or staying awake and other flu-like symptoms. Risks may include blood clots in the leg or lungs. In general, the benefits of raloxifene outweigh the risks in younger women who are not at increased risk of blood clots or stroke. Raloxifene is also FDA-approved for the prevention and treatment of osteoporosis.

Breast Density

Breast density refers to the amount of breast tissue in a given area of the breast as seen on mammography. Breasts that are very dense appear white on mammography, making cancers harder to see. In addition, women with very dense breasts have a slightly higher risk of developing breast cancer compared to women with low breast density.

Women with very dense breasts who are also at increased risk for breast cancer may benefit from digital screening mammography as well as breast ultrasound to increase the likelihood of detecting a breast cancer that is present.

Genetic Screening

About 5-10% of breast cancers are thought to be genetic, meaning they result from mutations in genes that can be passed from parent to child. The genes most commonly linked to an increased risk of breast cancer are the BRCA1 and BRCA2 genes. Mutations in these genes can be carried and passed on by both male and female members of a family. Mutations in these genes are associated with some other cancers including ovarian, prostate and pancreatic cancer and melanoma.

Clues that a family may carry a mutation in the BRCA1 or BRCA2 gene include:

  • Breast cancer in two or more family members
  • Breast cancer in a family member that was found before age 50
  • Family history of both breast and ovarian cancers, especially if they occurred in the same individual
  • Women diagnosed with breast cancer in both breasts
  • Ashkenazi Jewish families with breast cancer in one or more individuals
  • Male breast cancer

Cancer family history usually includes first or second degree relatives (mother, father, grandparents, brother, sister, aunt or uncle). If cancers are found in one of these relatives, information about additional family members may be obtained. If the family history suggests a possible gene mutation, genetic testing for specific mutations can be done using a single blood sample.

In addition to BRCA1 and BRCA2 genes, other gene mutations (CHEK2, MRE11A, CDH1, ATM, BRIP1, NBN, PALB2, PTEN, RAD51C, STK11, TP53, RAD50) have been linked to increased risk for breast cancer. These genes are even more rare than BRCA mutations, and do not increase breast cancer risk as much as abnormal BRCA genes do.

Having a gene mutation does not mean that you will get breast cancer, but it does mean that you are at higher risk for these cancers. Women known to carry BRCA1 or BRCA2 mutations can choose to have additional breast cancer screening (earlier or more frequent mammograms, breast MRI, breast ultrasound), take medications to reduce breast cancer risk (tamoxifen or raloxifene), or have risk-reducing surgery (mastectomy, removal of the ovaries). Younger women who have a gene mutation can take birth control pills to reduce their risk of ovarian cancer. There is currently no approved test for ovarian cancer screening, although several tests are being studied.

If you believe your family history may place you at increased risk for breast cancer, you may want to speak with a genetic counselor. The counselor will take a detailed family history, refer you for genetic testing if indicated, and make recommendations for cancer screening based on your family history.

Before deciding about genetic testing, it's important to weigh both the benefits and harms testing, especially the anxiety or worry that can occur from knowing and not knowing your genetic status. The impact of the test results on other family members may also be a consideration.

Breast Cancer Information and Support

Below are some useful websites for women who would like breast cancer information, support or are interested in breast cancer advocacy: