General Information About Breast Cancer

KEY POINTS

• Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.
• A family history of breast cancer and other factors increase the risk of breast cancer.
• Breast cancer is sometimes caused by inherited gene mutations (changes).
• The use of certain medicines and other factors decrease the risk of breast cancer.
• Signs of breast cancer include a lump or change in the breast.
• Tests that examine the breasts are used to diagnose breast cancer.
• If cancer is found, tests are done to study the cancer cells.
• Certain factors affect prognosis (chance of recovery) and treatment options.

Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.

The breast is made up of lobes and ducts. Each breast has 15 to 20 sections called lobes. Each lobe has many smaller sections called lobules. Lobules end in dozens of tiny bulbs that can make milk. The lobes, lobules, and bulbs are linked by thin tubes called ducts.

Each breast also has blood vessels and lymph vessels. The lymph vessels carry an almost colorless, watery fluid called lymph. Lymph vessels carry lymph between lymph nodes. Lymph nodes are small, bean-shaped structures found throughout the body. They filter lymph and store white blood cells that help fight infection and disease. Groups of lymph nodes are found near the breast in the axilla (under the arm), above the collarbone, and in the chest.

The most common type of breast cancer is ductal carcinoma, which begins in the cells of the ducts. Cancer that begins in the lobes or lobules is called lobular carcinoma and is more often found in both breasts than are other types of breast cancer. Inflammatory breast cancer is an uncommon type of breast cancer in which the breast is warm, red, and swollen.

What is breast cancer?

Breast cancer is a cancer that starts in breast tissue. It happens when cells in the breast change and grow out of control. The cells usually form a tumor.

Sometimes the cancer does not spread any further. This is called "in situ." If the cancer spreads outside the breast, the cancer is called "invasive." It may just spread to nearby tissues and lymph nodes. Or the cancer may metastasize (spread to other parts of the body) through the lymph system or the blood.

Breast cancer is the second most common type of cancer in women in the United States. Rarely, it can also affect men.

What are the types of breast cancer?

There are different types of breast cancer. The types are based on which breast cells turn into cancer. The types include:

• Ductal carcinoma, which begins in the cells of the ducts. This is the most common type.
• Lobular carcinoma, which begins in the lobules. It is more often found in both breasts than other types of breast cancer.
• Inflammatory breast cancer, in which cancer cells block lymph vessels in the skin of the breast. The breast becomes warm, red, and swollen. This is a rare type.
• Paget's disease of the breast, which is a cancer involving the skin of the nipple. It usually also affects the darker skin around the nipple. It is also rare.

What causes breast cancer?

Breast cancer happens when there are changes in the genetic material (DNA). Often, the exact cause of these genetic changes is unknown.

But sometimes these genetic changes are inherited, meaning that you are born with them. Breast cancer that is caused by inherited genetic changes is called hereditary breast cancer.

There are also certain genetic changes that can raise your risk of breast cancer, including changes in the BRCA1 and BRCA2 genes. These two changes also raise your risk of ovarian and other cancers.

Besides genetics, your lifestyle and the environment can affect your risk of breast cancer.

Who is at risk for breast cancer?

The factors that raise your risk of breast cancer include:

• Older age
• History of breast cancer or benign (noncancer) breast disease
• Inherited risk of breast cancer, including having BRCA1 and BRCA2 gene changes
• Dense breast tissue
• A reproductive history that leads to more exposure to the estrogen hormone, including
  • Menstruating at an early age
  • Being at an older age when you first gave birth or never having given birth
  • Starting menopause at a later age
• Taking hormone therapy for symptoms of menopause
• Radiation therapy to the breast or chest
• Obesity
• Drinking alcohol

What are the signs and symptoms of breast cancer?

The signs and symptoms of breast cancer include:

• A new lump or thickening in or near the breast or in the armpit.
• A change in the size or shape of the breast.
• A dimple or puckering in the skin of the breast. It may look like the skin of an orange.
• A nipple turned inward into the breast.
• Nipple discharge other than breast milk. The discharge might happen suddenly, be bloody, or happen in only one breast.
• Scaly, red, or swollen skin in the nipple area or the breast
• Pain in any area of the breast.

How is breast cancer diagnosed?

Your health care provider may use many tools to diagnose breast cancer and figure out which type you have:

• A physical exam, including a clinical breast exam (CBE). This involves checking for any lumps or anything else that seems unusual with the breasts and armpits.
• A medical history.
• Imaging tests, such as a mammogram, an ultrasound, or an MRI.
• Breast biopsy.
• Blood chemistry tests, which measure different substances in the blood, including electrolytes, fats, proteins, glucose (sugar), and enzymes. Some of the specific blood chemistry tests include a basic metabolic panel (BMP), a comprehensive metabolic panel (CMP), and an electrolyte panel.

If these tests show that you have breast cancer, you will have tests that study the cancer cells. These tests help your provider decide which treatment would be best for you. The tests may include:

• Genetic tests for genetic changes such as in the BRCA and TP53 genes.
• HER2 test. HER2 is a protein involved with cell growth. It is on the outside of all breast cells. If your breast cancer cells have more HER2 than normal, they can grow more quickly and spread to other parts of the body.
• An estrogen and progesterone receptor test. This test measures the amount of estrogen and progesterone (hormones) receptors in cancer tissue. If there are more receptors than normal, the cancer is called estrogen and/or progesterone receptor positive. This type of breast cancer may grow more quickly.

Another step is staging the cancer. Staging involves doing tests to find out whether the cancer has spread within the breast or to other parts of the body. The tests may include other diagnostic imaging tests and a sentinel lymph node biopsy. This biopsy is done to see whether the cancer has spread to the lymph nodes.

What are the treatments for breast cancer?

Treatments for breast cancer include:

• Surgery such as
  • A mastectomy, which removes the whole breast
  • A lumpectomy to remove the cancer and some normal tissue around it, but not the breast itself
• Radiation therapy
• Chemotherapy
• Hormone therapy, which blocks cancer cells from getting the hormones they need to grow
• Targeted therapy, which uses drugs or other substances that attack specific cancer cells with less harm to normal cells
• Immunotherapy

Can breast cancer be prevented?

You may be able to help prevent breast cancer by making healthy lifestyle changes such as:

• Staying at a healthy weight
• Limiting alcohol use
• Getting enough exercisee
• Limiting your exposure to estrogen by
  • Breastfeeding your babies if you can
  • Limiting hormone therapy

If you are at high risk, your health care provider may suggest that you take certain medicines to lower the risk. Some women at very high risk may decide to get a mastectomy (of their healthy breasts) to prevent breast cancer.

It's also important to get regular mammograms. They may be able to identify breast cancer in the early stages, when it is easier to treat.

Health Fast Facts

99%

If breast cancer is confined to the breast, the 5-year survival rate is 99%.

Breast cancer affects one in eight women in the U.S. and is the second most common type of cancer diagnosed in women, after skin cancer.

The good news is that breast cancer death rates slowly fell each year from 2008 to 2017. But more screening could help those rates drop faster.

How it happens

Breast cancer happens when cancerous cells form in the breast tissue. Health experts don't know exactly why cancerous cells form in the breast in some women but not others. However, they do know some of the risk factors, such as older age, smoking, and a family history of the disease.

Estimating risk

Some women who don't seem to have common risk factors may still develop the disease, while other women with a known risk factor may never develop it. This is why regular screening, such as mammograms, is key. Treatment for breast cancer is most effective and provides the best chance of survival when the disease is caught early.

Screening rates

Screening rates are increasing in some groups of women in the U.S. But for other groups, the rates are declining. According to the National Cancer Institute, screening rates have increased slightly among Hispanic women, but have dropped among other groups, including Asian women, women in rural areas, and women with public health insurance or no health insurance.

Who is more likely to get it?

• Breast cancer is most common in middle-aged and older women.
• Women aged 45 to 54 make up nearly 20% of new cases. Women aged 55 to 74 make up 51% of new cases.
• The rate of new cases of breast cancer is highest in white women, followed by African American women. Breast cancer death rates are highest for African American women—40% higher than for white women.

How to lower your risk

The key is to get regular exams and screening. You can't do much about risk factors like age or family history of breast cancer. But there are other things you can do. These include:

• Controlling your weight. Those who are obese have a 20% to 40% higher risk of developing breast cancer compared with women whose weight is in the normal range.
• Limiting alcohol. Even one daily drink can raise your risk.
• Getting regular exercise.
• Quitting smoking.

More women are beating breast cancer these days, in part because of improved treatments and screening. When abnormal tissue or cancer is found in its early stages, it may be easier to treat.

NIH-funded scientists are searching for better ways to diagnose, treat, and even prevent breast cancer. Some are studying cancer at the cellular level to learn which tumors pose little danger and can be left alone. Others are developing targeted therapies with fewer side effects and seeking ways to boost survival. Certain drugs are already being used to help prevent breast cancer in some women at greatest risk.

Breast cancer is the second most common kind of cancer among women (after skin cancer). Men can get breast cancer too, although it’s rare. A woman’s risk of developing breast cancer rises as she gets older. Family and personal health history also affect her chances. Risk increases if a close relative has been diagnosed. Risk also goes up the longer a woman is exposed to the hormone estrogen. This means that risk is greater the earlier a woman starts menstruating, the later in life she has her first child, and the later she enters menopause. Exposure to radiation and other environmental factors can also raise the risk of breast cancer.

Warning signs of breast cancer can sometimes be seen or felt. Symptoms include a lump in the breast or armpit, breast pain, unusually firm breast skin, nipple discharge, or changes in the size or shape of the breast. Having one or more of these symptoms doesn’t necessarily indicate cancer. In fact, most lumps are not cancerous. But any of these changes should be discussed with a doctor.

Even before symptoms appear, screening tests can check for early cancer. Mammograms, or X-ray images of the breast, have helped reduce the number of deaths from breast cancer among women ages 40 to 70, especially those over age 50.

“Mammograms decrease the risk of dying of breast cancer, although no screening test is perfect,” says Dr. Barry Kramer, who heads cancer prevention research at NIH.

Mammograms, though, can have some drawbacks. Sometimes mammograms detect tumors that may not cause harm in the long run but are treated anyway. In these cases, women might receive toxic therapies for tumors that weren’t really a threat to their health. In addition, mammograms can sometimes have “false-positive” results; the tissue may look abnormal even though no cancer is present. False-positives can cause fear and anxiety and may lead to unnecessary follow-up testing.

Despite these concerns, mammograms remain an effective screening test. “Mammograms detect 80–85% of all breast cancers,” says Dr. Powel Brown, a breast oncologist at MD Anderson Cancer Center in Houston. “It’s still the best screening test we have, although imaging tests such as breast MRI, ultrasound, and breast tomograms are also being used, particularly in high-risk women.”

Experts recommend that women consult a health care provider at age 40, discuss their risks, and together decide when it’s best to start mammogram screening. Some women may not need to start these tests until age 50. “Screening, like treatment, should be individualized,” Brown says.

“Data shows an approximately 20% relative reduction in death for women who start getting mammograms at age 50 and have them every year or 2,” says Dr. Leslie Ford, who specializes in clinical research and cancer prevention at NIH.

When early-stage breast cancer is detected, the main treatments are surgery and radiation. A lumpectomy removes the affected area, but some women need a mastectomy, removal of the whole breast. Chemotherapy, or cancer-fighting medications, may also be used before or after surgery. In some cases, oncologists use targeted drugs or hormone therapy to treat certain types of tumors.

Once cancer spreads to other parts of the body, there’s no effective cure. Still, new therapies can control metastatic breast cancer to prolong life. Last year, one NIH-funded study found that a combination of 2 drugs can lengthen the lives of postmenopausal women with the most common type of metastatic breast cancer.

When it comes to preventing breast cancer, strategies can vary depending on each woman’s risk. Women at greatest risk include those who’ve already had cancer in one breast and those with a mother, sister, or daughter who’s had breast cancer, especially if they were diagnosed before age 50.

“If you have a strong family history of breast or ovarian cancer, get evaluated by a genetic expert,” Brown recommends. One genetic test looks at the BRCA genes. Women with certain BRCA mutations have a greatly increased risk of developing breast cancer, a risk that rises with age.

“If a woman has a BRCA mutation, she’s faced with deciding at what age to deal with it and how,” says Ford. “She must decide between preventive surgery and monitoring it closely.”

Preventive mastectomy—or surgical removal of a seemingly healthy breast—is an option for women at very high risk for breast cancer. A woman considering this aggressive surgery should talk with her doctor about her cancer risk, the surgical procedure, its potential complications, and alternatives to surgery.

Studies have shown that reducing prolonged exposure to the hormone estrogen might be another way to lower the risk of breast cancer. One preventive approach is to take medicine that blocks the effects of estrogen. Two such drugs, tamoxifen and raloxifene, are sometimes given to women at high risk for breast cancer. Raloxifene can only be given to postmenopausal women. Both of these medicines can have serious side effects. Still, their potential benefits for both prevention and treatment are encouraging. Large NIH-funded primary prevention studies of women at increased risk for breast cancer showed that “tamoxifen and raloxifene each reduced the risk of developing breast cancer by about 50%,” says Ford.

The drug exemestane, which decreases the amount of estrogen produced by the body, also shows promise for preventing breast cancer in at-risk postmenopausal women. Exemestane is usually given after breast cancer treatment to reduce the risk of the cancer returning.

“It’s a lost opportunity to not use these medicines,” says Brown. Women at elevated risk of breast cancer should talk with their doctor about the potential benefits and harms of taking these preventive medicines.

No matter what your risk for breast cancer, you can make healthy changes that might lower your chances of getting the disease. Eat a heart-healthy diet, reduce alcohol intake, don’t smoke, and get regular exercise. Talk to a health care provider about how you might lower your risk of cancer.

Talk To Your Doctor

• if you notice a lump or firm tissue on your breast or under your arm.
• if you see a change in the size or shape of your breast.
• if cancer runs in your family.
• about when to start and how often to get mammograms.
• about treatment choices and possible risks if you’ve been diagnosed
• about clinical research trials.

Breast cancer is the second most common cancer among American women. Breast cancer death rates have been falling over the past 30 years. But nearly 13% of women are still diagnosed in their lifetime. Men can get breast cancer too, although it’s rare.

Cancer is caused by changes to genes that control the way our cells function. These changes affect how cells grow and divide. Cancer results when cells divide uncontrollably. In breast cancer, this happens in the breast tissue.

Researchers are studying the risk factors for different types of breast cancer. They’re also searching for more personalized treatments.

Unraveling The Risks

“Breast cancer is caused by a combination of factors,” says Dr. Montserrat García-Closas, a cancer researcher at NIH. Your genes, lifestyle, and environment all contribute to your risk. Researchers are trying to better understand how each plays a role.

People with a family history of breast cancer are at increased risk for the disease. Some are born with rare versions of certain genes that put them at high risk. These include the genes BRCA1 and BRCA2.

“But the vast majority of patients have no known family history and no known gene that causes cancer,” explains Dr. Margaret Gatti-Mays, a breast cancer treatment specialist at The Ohio State University.

So researchers are also searching for combinations of genes that may lead to breast cancer. “Women can inherit hundreds or thousands of common versions of genes that each have tiny effects, but in combination can put them at substantial risk for developing breast cancer,” García-Closas says. An NIH study called the Confluence Project is trying to unravel these combinations.

Other factors can increase your risk for breast cancer, too. These include your age, whether you’ve had children, alcohol use, and obesity.

Studies are examining how all these factors—genes, medical history, and lifestyle—interact to affect cancer risk. One is called Connect for Cancer Prevention. “It’s recruiting 200,000 people in the U.S. and following them for years to see who develops different types of cancers,” says García-Closas.

Staying Ahead of Breast Cancer

Another study, called the Wisdom Study, is exploring how to best personalize breast cancer screening. Screening tests look for signs of a disease before symptoms appear. Finding cancer early may increase the chance that it can be treated and cured.

If you’re at high risk for breast cancer, your doctor may advise you to get screenings at an earlier age than most, or more often.

“Women from 40 to 50 should talk with their doctor about when they should start screening. And that should be based on their personal risks,” says Dr. Brandy Heckman-Stoddard, an NIH expert on breast cancer.

Mammograms are the most common way to screen for breast cancer. These are X-ray pictures of the breast. An NIH study called TMIST is comparing whether 2D or 3D mammograms are better for screening. 2D mammograms are taken from two sides of the breast. 3D mammograms are taken from different angles around the breast. Then, a computer builds a 3D-like image.

Magnetic resonance imaging (MRI) is sometimes used to screen women at high risk of breast cancer. MRIs can create a clearer image of the breast and don’t use radiation.

Researchers are looking for other ways to detect breast cancer, too. García-Closas’ team is trying to detect cancer using blood samples. These “liquid biopsies” detect DNA from cancer cells, which travel around the body in the bloodstream.

“Liquid biopsies should reflect what’s going on in your whole body,” García-Closas says, “versus when you look at a tissue biopsy, you’re taking a tiny sample of tissue in a particular location.”

Liquid biopsies may one day be able to detect cancer before other clinical tests, she says. “And, they might be able to better monitor what’s happening in your body after cancer has been diagnosed.”

Fighting Back

When breast cancer is found, treatment depends on the type of tumor. Surgery and radiation are common. Chemotherapy may also be used. Doctors might recommend other treatments as well, depending on the type of breast cancer.

“There are three main types of breast cancer,” Gatti-Mays says. “The subtype is determined by the presence or absence of three receptors .” These receptors respond to the hormones estrogen or progesterone or a protein called HER2.

“If your tumor has estrogen and progesterone receptors, then you can be treated with hormone therapies,” says Heckman-Stoddard. These block the action of hormones that can cause certain cancers to grow.

Hormone treatments can also be used to prevent or lower the risk of cancer for certain women. One such drug is called tamoxifen. But it has side effects that make it unappealing for prevention. Heckman-Stoddard’s team is studying whether using the drug as a gel lessens the side effects.

There are newer treatment options called targeted treatments. These block specific proteins that control how cancer cells grow, divide, and spread. Targeted treatments for HER2-positive cancer have improved survival over the last decade.

The most recent type of cancer treatment is called immunotherapy. It trains your body to fight cancer using your own immune system .

“Immunotherapy is very promising, but the benefits are still limited to only some patients with triple negative breast cancer,” says Gatti-Mays. These cancers lack all three receptors. But researchers are trying to expand this treatment to more patients with breast cancer. They’re also testing whether using it in combination with other treatments will work better.

Scientists continue to look for ways to improve screening, prevention, and treatment. “In the next five to 10 years, there should be better ways for women to determine their risk of breast cancer,” says García-Closas. “That should help them have a conversation with their physicians on what will be the best tailored prevention strategies.”

No matter what your personal risk of cancer, a healthy lifestyle is the best way to prevent it. Eat a heart-healthy diet, reduce alcohol intake, don’t smoke, and get regular exercise. See the Wise Choices box and talk with your health care provider about ways to lower your risk.

Ask Your Doctor About Your Breast Cancer Risk

Certain factors put you at higher risk for breast cancer. These include:

• Being 40 years old or older
• A personal history of breast cancer or benign (noncancer) breast disease
• Radiation exposure to the breast or chest
• Having a close relative who’s had breast cancer
• Greater exposure to estrogen over time. (Starting menstruation early or entering menopause later in life.)
• Hormone therapy for symptoms of menopause
• Obesity
• Drinking alcohol

Whereas the breasts are located far from the other female reproductive organs, they are considered accessory organs of the female reproductive system. The function of the breasts is to supply milk to an infant in a process called lactation. The external features of the breast include a nipple surrounded by a pigmented areola, whose coloration may deepen during pregnancy. The areola is typically circular and can vary in size from 25 to 100 mm in diameter. The areolar region is characterized by small, raised areolar glands that secrete lubricating fluid during lactation to protect the nipple from chafing. When a baby nurses, or draws milk from the breast, the entire areolar region is taken into the mouth.

Breast milk is produced by the mammary glands, which are modified sweat glands. The milk itself exits the breast through the nipple via 15 to 20 lactiferous ducts that open on the surface of the nipple. These lactiferous ducts each extend to a lactiferous sinus that connects to a glandular lobe within the breast itself that contains groups of milk-secreting cells in clusters called alveoli. The clusters can change in size depending on the amount of milk in the alveolar lumen. Once milk is made in the alveoli, stimulated myoepithelial cells that surround the alveoli contract to push the milk to the lactiferous sinuses. From here, the baby can draw milk through the lactiferous ducts by suckling. The lobes themselves are surrounded by fat tissue, which determines the size of the breast; breast size differs between individuals and does not affect the amount of milk produced. Supporting the breasts are multiple bands of connective tissue called suspensory ligaments that connect the breast tissue to the dermis of the overlying skin.

During the normal hormonal fluctuations in the menstrual cycle, breast tissue responds to changing levels of estrogen and progesterone, which can lead to swelling and breast tenderness in some individuals, especially during the secretory phase. If pregnancy occurs, the increase in hormones leads to further development of the mammary tissue and enlargement of the breasts.

What are dense breasts?

Breasts contain glandular tissue, fibrous connective tissue, and fatty breast tissue. Breast density is a term that describes the relative amount of these different types of breast tissue as seen on a mammogram. Dense breasts have relatively high amounts of glandular tissue and fibrous connective tissue and relatively low amounts of fatty breast tissue.

Are dense breasts common?

Yes, dense breasts are common. Nearly half of all women who are 40 and older who get mammograms are found to have dense breasts.

What factors influence breast density

Breast density is often inherited, but other factors can influence it.

• Factors associated with higher breast density include using menopausal hormone therapy and having a low body mass index.
• Factors associated with lower breast density include increasing age and having children.

How do I know if I have dense breasts?

Dense breast tissue cannot be felt by a woman, such as during a breast self-exam, or by her doctor during a clinical breast exam. Only a radiologist looking at a mammogram can tell if a woman has dense breasts. Dense breasts are sometimes called mammographically dense breasts.

How is breast density categorized in a mammogram report?

Doctors use the Breast Imaging Reporting and Data System (BI-RADS) to classify breast density. This system, developed by the American College of Radiology, helps doctors interpret and report back mammogram findings. Doctors who review mammograms are called radiologists. BI-RADS classifies breast density into four categories:

• Entirely fatty breast tissue: There is almost all fatty breast tissue. It is found in about 10% of women.
• Scattered fibroglandular breast tissue: There is mostly fatty tissue with some areas of dense glandular and fibrous connective tissue. It is found in about 40% of women.
• Heterogeneously dense breast tissue: There are many areas of dense glandular and fibrous connective tissue, with some areas of fatty tissue. It is found in about 40% of women
• Extremely dense breast tissue: There is almost all dense glandular and fibrous connective tissue. It is found in about 10% of women.

If your mammogram report letter says you have dense breasts, it means that you have either heterogeneously dense breast tissue or extremely dense breast tissue.

Does having dense breast tissue affect a mammogram?

Dense breasts can make a mammogram more difficult to interpret. That's because dense breast tissue and some abnormal breast changes, such as calcifications and tumors, both appear as white areas in the mammogram, whereas fatty tissue appears as dark areas.

As a result, mammography is less sensitive in women with dense breasts—that is, it is more likely to miss cancer. Women with dense breasts may be called back for follow-up testing more often than women with fatty breasts.

Are dense breasts a risk factor for breast cancer?

Dense breasts are not considered an abnormal breast condition or a disease. However, dense breasts are a risk factor for breast cancer. That is, women with dense breasts have a higher risk of breast cancer than women with fatty breasts. This risk is separate from the effect of dense breasts on the ability to read a mammogram.

In most states, mammography providers are required to inform women if they have dense breasts.

Should women with dense breasts have additional screening for breast cancer?

The value of additional, or supplemental, imaging tests such as ultrasound or MRI to screen for breast cancer in women with dense breasts is not yet clear, according to the Recommendation Statement on Breast Cancer Screening by the United States Preventive Services Task Force (USPSTF). Talk with your doctor or nurse to learn what is recommended for you, based on your personal medical history and family medical history.

Are breast cancer patients with dense breasts more likely to die from breast cancer?

No. Research has found that breast cancer patients who have dense breasts are no more likely to die from breast cancer than breast cancer patients who have fatty breasts, after accounting for other health factors and tumor characteristics.

Questions to consider asking your doctor or nurse

Ask these questions to get information that’s specific to you, based on your personal medical history:

• What are the dense breast-related findings in my recent mammogram?
• Do you recommend additional screening or diagnostic tests for me?
• What is my overall personal risk of breast cancer, given my risk and protective factors?

Are there clinical trials for women with dense breasts?

Yes, there are ongoing and completed clinical trials related to dense breasts that are studying better ways to detect breast cancer in women with dense breasts.

What are researchers studying about the relationship between breast density and breast cancer?

Here are some questions that researchers are working to answer:

• Can imaging tests such as 3-D mammography, MRI, ultrasound, or other imaging procedures help provide a clearer picture of breast density?
• Are there certain patterns or areas of dense breast tissue that are particularly “risky”?
• Why do some women with dense breasts develop breast cancer, whereas others do not?
• What biologic mechanisms explain the association between high breast density and increased breast cancer risk?
• Can biomarkers be identified that may help predict whether breast cancer will develop in a woman with dense breasts?
• Are changes in breast density over time associated with changes in breast cancer risk?
• Can women reduce their breast density, and potentially their risk of developing or dying from breast cancer, by taking medicines or by applying topical agents on their breasts?

Breast cancer screening means checking a woman’s breasts for cancer before there are signs or symptoms of the disease. All women need to be informed by their health care provider about the best screening options for them. When you are told about the benefits and risks of screening and decide with your health care provider whether screening is right for you—and if so, when to have it—this is called informed and shared decision-making.

Although breast cancer screening cannot prevent breast cancer, it can help find breast cancer early, when it is easier to treat. Talk to your doctor about which breast cancer screening tests are right for you, and when you should have them.

Breast Cancer Screening Recommendations

The United States Preventive Services Task Force (USPSTF) is an organization made up of doctors and disease experts who look at research on the best way to prevent diseases and make recommendations on how doctors can help patients avoid diseases or find them early.

The USPSTF recommends that women who are 50 to 74 years old and are at average risk for breast cancer get a mammogram every two years. Women who are 40 to 49 years old should talk to their doctor or other health care professional about when to start and how often to get a mammogram. Women should weigh the benefits and risks of screening tests when deciding whether to begin getting mammograms before age 50.

Breast Cancer Screening Tests

Mammogram

A mammogram is an X-ray of the breast. Mammograms are the best way to find breast cancer early, when it is easier to treat and before it is big enough to feel or cause symptoms. Having regular mammograms can lower the risk of dying from breast cancer. At this time, a mammogram is the best way to find breast cancer for most women.

Breast Magnetic Resonance Imaging (MRI)

A breast MRI uses magnets and radio waves to take pictures of the breast. MRI is used along with mammograms to screen women who are at high risk for getting breast cancer. Because breast MRIs may appear abnormal even when there is no cancer, they are not used for women at average risk.

Other Exams

Clinical Breast Exam

A clinical breast exam is an examination by a doctor or nurse, who uses his or her hands to feel for lumps or other changes.

Breast Self-Awareness

Being familiar with how your breasts look and feel can help you notice symptoms such as lumps, pain, or changes in size that may be of concern. These could include changes found during a breast self-exam. You should report any changes that you notice to your doctor or health care provider.

Having a clinical breast exam or doing a breast self-exam has not been found to lower the risk of dying from breast cancer.

Benefits and Risks of Screening

Every screening test has benefits and risks, which is why it’s important to talk to your doctor before getting any screening test, like a mammogram.

Benefit of Screening

The benefit of screening is finding cancer early, when it’s easier to treat.

Risks of Screening

Harms can include false positive test results, when a doctor sees something that looks like cancer but is not. This can lead to more tests, which can be expensive, invasive, time-consuming, and may cause anxiety.

Tests also can lead to overdiagnosis, when doctors find a cancer that would not have gone on to cause symptoms or problems, or even may go away on its own. Treatment of these cancers is called overtreatment. Overtreatment can include treatments recommended for breast cancer, such as surgery or radiation therapy. These can cause unnecessary and unwanted side effects. Other potential harms from breast cancer screening include pain during the procedure and radiation exposure from the mammogram test itself. While the amount of radiation in a mammogram is small, there may be risks with having repeated X-rays.

Mammograms may also miss some cancers, called false negative test results, which may delay finding a cancer and getting treatment.