Breast Cancer

Breast cancer is the second most common cancer in women after skin cancer. Mammograms can detect breast cancer early, possibly before it has spread.

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, which have 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 that 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.

Breast cancer is the second most common type of cancer in American women.

Women in the United States get breast cancer more than any other type of cancer except skin cancer. Breast cancer is second to lung cancer as a cause of cancer death in American women. However, deaths from breast cancer have decreased a little bit every year between 2007 and 2016. Breast cancer also occurs in men, but the number of new cases is small. Scroll down for further information.

Changes to your breasts

Breast Changes of Concern

Some breast changes can be felt by a woman or her health care provider, but most can be detected only during an imaging procedure such as a mammogram, MRI, or ultrasound. Whether a breast change was found by your doctor or you noticed a change, it’s important to follow up with your doctor to have the change checked and properly diagnosed.

Check with your health care provider if your breast looks or feels different, or if you notice one of these symptoms:

• Lump or firm feeling in your breast or under your arm. Lumps come in different shapes and sizes. Normal breast tissue can sometimes feel lumpy. Doing breast self-exams can help you learn how your breasts normally feel and make it easier to notice and find any changes, but breast self-exams are not a substitute for mammograms.
• Nipple changes or discharge. Nipple discharge may be different colors or textures. It can be caused by birth control pills, some medicines, and infections. But because it can also be a sign of cancer, it should always be checked.
• Skin that is itchy, red, scaled, dimpled or puckered

Breast Changes During Your Lifetime That Are Not Cancer

Most women have changes in the breasts at different times during their lifetime.

• Before or during your menstrual periods, your breasts may feel swollen, tender, or painful. You may also feel one or more lumps during this time because of extra fluid in your breasts. Your health care provider may have you come back for a return visit at a different time in your menstrual cycle to see if the lump has changed.
• During pregnancy, your breasts may feel lumpy. This is usually because the glands that produce milk are increasing in number and getting larger. While breastfeeding, you may get a condition called mastitis. This happens when a milk duct becomes blocked. Mastitis causes the breast to look red and feel lumpy, warm, and tender. It may be caused by an infection and it is often treated with antibiotics. Sometimes the duct may need to be drained.
• As you approach menopause, your hormone levels change. This can make your breasts feel tender, even when you are not having your menstrual period. Your breasts may also feel more lumpy than they did before.
• If you are taking hormones (such as menopausal hormone therapy, birth control pills, or injections) your breasts may become more dense. This can make a mammogram harder to interpret. Be sure to let your health care provider know if you are taking hormones.
• After menopause, your hormone levels drop. You may stop having any lumps, pain, or nipple discharge that you used to have.

Mammogram Findings

Mammograms are pictures (x-rays) of the breast, used to check for breast cancer. Possible mammogram findings include:

• Lumps (mass or tumor). Lumps come in different sizes and shapes. Fluid-filled cysts are usually smooth and rounded, with clear, defined edges and are not cancer. Lumps that have a jagged outline and an irregular shape are of more concern.
• Calcifications. There are two types of breast calcifications, or calcium deposits:
  • Macrocalcifications, which look like small white dots on a mammogram. They are often caused by aging, an old injury, or inflammation and are usually benign.
  • Microcalcifications, which look like white specks on a mammogram. If found in an area of rapidly dividing cells or grouped together in a certain way, they may be a sign of DCIS or breast cancer.
• Dense breast tissue: A dense breast has relatively less fat and more glandular and connective tissue. This mammogram finding is both common and normal, especially among younger women and women who use menopausal hormone therapy. Dense breast tissue can make a mammogram more difficult to interpret because both dense breast tissue and breast tumors appear as solid white areas in the image. 

Follow-up tests to diagnose breast changes

The procedures and tests listed below may be recommended by your health care provider to help diagnose a breast change that was found on a mammogram or that you or your health care provider felt.

Diagnostic mammography: A type of mammography in which more x-ray pictures of the breast are taken from different angles to allow a possible abnormality to be examined more closely.

Ultrasound: A procedure that makes a picture (called a sonogram) of breast tissue in order to find out if a lump is solid or is filled with fluid (that is, a cyst). Pictures are made using sound waves.

MRI (also called Magnetic Resonance Imaging): A procedure that uses a powerful magnet, radio waves, and a computer to take detailed pictures of areas inside the breast. An MRI can be used to learn more about breast lumps or large lymph nodes that were found during a clinical breast exam or breast self-exam but were not seen on a mammogram or ultrasound.

Ductography (also called a galactography): A procedure that takes pictures of the breast ducts, so that doctors can learn more about certain kinds of abnormal nipple discharge or masses such as intraductal papillomas (wart-like tumors that are benign). Pictures of the breast ducts are taken using a contrast material that is given through an injection to help breast ducts show up clearly.

Biopsy: A procedure that removes a sample of breast tissue or an entire lump so that it can be checked for signs of disease. Imaging procedures (such as ultrasound, MRIs, or x-rays) are often used during a biopsy to guide the surgeon. A pathologist then examines the sample under a microscope or performs other tests on it. Common types of breast biopsies include:

• Core needle biopsy: The use of a wide needle to remove small tissue sample(s) that are about the size of a grain of rice. It may cause a temporary bruise. Also called core biopsy.
• Fine-needle aspiration biopsy: The use of a thin needle to drain fluid and/or to remove cells.
• Surgical biopsy: The removal of part, or all, of a lump so it can be checked for signs of cancer. An incisional biopsy removes a sample of breast tissue. An excisional biopsy removes an entire lump or suspicious area. Wire localization (also called needle localization and needle (wire) localization) may be used to mark the area of abnormal tissue before the biopsy.
• Vacuum-assisted biopsy: The removal of a small sample of breast tissue using a probe that is connected to a vacuum device. The small cut made in the breast is much smaller than with surgical biopsy. This procedure causes little scarring, and no stitches are needed. It may also be called vacuum-assisted core biopsy.

Biopsies are usually done in a doctor’s office or a clinic on an outpatient basis. This means you will go home the same day as the procedure. Local anesthesia is used for many biopsies, so you’ll be awake but won’t feel pain during the procedure. General anesthesia is commonly used for surgical biopsies, which means you’ll be asleep during the procedure.

Follow this link for an extensive list of breast conditions

Breast Cancer Prevention and Risk

Key Points

• Avoiding risk factors and increasing protective factors may help prevent cancer.
• The following are risk factors for breast cancer:
  • Older age
  • A personal history of breast cancer or benign (noncancer) breast disease
  • Inherited risk of breast cancer
  • Dense breasts
  • Exposure of breast tissue to estrogen made in the body
  • Taking hormone therapy for symptoms of menopause
  • Radiation therapy to the breast or chest
  • Obesity
  • Drinking alcohol
• The following are protective factors for breast cancer:
  • Less exposure of breast tissue to estrogen made by the body
  • Taking estrogen-only hormone therapy after hysterectomy, selective estrogen receptor modulators, or aromatase inhibitors and inactivators
    • Estrogen-only hormone therapy after hysterectomy
    • Selective estrogen receptor modulators
    • Aromatase inhibitors and inactivators
  • Risk-reducing mastectomy
  • Ovarian ablation
  • Getting enough exercise
• It is not clear whether the following affect the risk of breast cancer:
  • Hormonal contraceptives
  • Environment
• Studies have shown that some factors have little or no effect on the risk of breast cancer.
• Cancer prevention clinical trials are used to study ways to prevent cancer.
• New ways to prevent breast cancer are being studied in clinical trials.

Avoiding risk factors and increasing protective factors may help prevent cancer.

Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.

The following are risk factors for breast cancer:

Older age

Older age is the main risk factor for most cancers. The chance of getting cancer increases as you get older.

A personal history of breast cancer or benign (noncancer) breast disease

Women with any of the following have an increased risk of breast cancer:

• A personal history of invasive breast cancer, ductal carcinoma in situ (DCIS), or lobular carcinoma in situ (LCIS).
• A personal history of benign (noncancer) breast disease.

Inherited risk of breast cancer

Women with a family history of breast cancer in a first-degree relative (mother, sister, or daughter) have an increased risk of breast cancer.

Women who have inherited changes in the BRCA1 and BRCA2 genes or in certain other genes have a higher risk of breast cancer. The risk of breast cancer caused by inherited gene changes depends on the type of gene mutation, family history of cancer, and other factors.

Dense breasts

Having breast tissue that is dense on a mammogram is a factor in breast cancer risk. The level of risk depends on how dense the breast tissue is. Women with very dense breasts have a higher risk of breast cancer than women with low breast density.

Increased breast density is often an inherited trait, but it may also occur in women who have not had children, have a first pregnancy late in life, take postmenopausal hormones, or drink alcohol.

Exposure of breast tissue to estrogen made in the body

Estrogen is a hormone made by the body. It helps the body develop and maintain female sex characteristics. Being exposed to estrogen over a long time may increase the risk of breast cancer. Estrogen levels are highest during the years a woman is menstruating.

A woman’s exposure to estrogen is increased in the following ways:

• Early menstruation: Beginning to have menstrual periods at age 11 or younger increases the number of years the breast tissue is exposed to estrogen.
• Starting menopause at a later age: The more years a woman menstruates, the longer her breast tissue is exposed to estrogen.
• Older age at first birth or never having given birth: Because estrogen levels are lower during pregnancy, breast tissue is exposed to more estrogen in women who become pregnant for the first time after age 35 or who never become pregnant.

Taking hormone therapy for symptoms of menopause

Hormones, such as estrogen and progesterone, can be made into a pill form in a laboratory. Estrogen, progestin, or both may be given to replace the estrogen no longer made by the ovaries in postmenopausal women or women who have had their ovaries removed. This is called hormone replacement therapy (HRT) or hormone therapy (HT).

Combination HRT/HT is estrogen combined with progestin. This type of HRT/HT increases the risk of breast cancer. Studies show that when women stop taking estrogen combined with progestin, the risk of breast cancer decreases.

Radiation therapy to the breast or chest

Radiation therapy to the chest for the treatment of cancer increases the risk of breast cancer, starting 10 years after treatment. The risk of breast cancer depends on the dose of radiation and the age at which it is given. The risk is highest if radiation treatment was used during puberty, when breasts are forming.

Radiation therapy to treat cancer in one breast does not appear to increase the risk of cancer in the other breast.

For women who have inherited changes in the BRCA1 and BRCA2 genes, exposure to radiation, such as that from chest x-rays, may further increase the risk of breast cancer, especially in women who were x-rayed before 20 years of age.

Obesity

Obesity increases the risk of breast cancer, especially in postmenopausal women who have not used hormone replacement therapy.

Drinking alcohol

Drinking alcohol increases the risk of breast cancer. The level of risk rises as the amount of alcohol consumed rises.

The following are protective factors for breast cancer:

Less exposure of breast tissue to estrogen made by the body

Decreasing the length of time a woman’s breast tissue is exposed to estrogen may help prevent breast cancer. Exposure to estrogen is reduced in the following ways:

• Early pregnancy: Estrogen levels are lower during pregnancy. Women who have a full-term pregnancy before age 20 have a lower risk of breast cancer than women who have not had children or who give birth to their first child after age 35.
• Breast-feeding: Estrogen levels may remain lower while a woman is breast-feeding. Women who breastfed have a lower risk of breast cancer than women who have had children but did not breastfeed.

Taking estrogen-only hormone therapy after hysterectomy, selective estrogen receptor modulators, or aromatase inhibitors and inactivators

Hormone therapy with estrogen only may be given to women who have had a hysterectomy. In these women, estrogen-only therapy after menopause may decrease the risk of breast cancer. There is an increased risk of stroke and heart and blood vessel disease in postmenopausal women who take estrogen after a hysterectomy.

Selective estrogen receptor modulators

Tamoxifen and raloxifene belong to the family of drugs called selective estrogen receptor modulators (SERMs). SERMs act like estrogen on some tissues in the body, but block the effect of estrogen on other tissues.

Treatment with tamoxifen lowers the risk of estrogen receptor-positive (ER-positive) breast cancer and ductal carcinoma in situ in premenopausal and postmenopausal women at high risk. Treatment with raloxifene also lowers the risk of breast cancer in postmenopausal women. With either drug, the reduced risk lasts for several years or longer after treatment is stopped. Lower rates of broken bones have been noted in patients taking raloxifene.

Taking tamoxifen increases the risk of hot flashes, endometrial cancer, stroke, cataracts, and blood clots (especially in the lungs and legs). The risk of having these problems increases markedly in women older than 50 years compared with younger women. Women younger than 50 years who have a high risk of breast cancer may benefit the most from taking tamoxifen.

The risk of having these problems decreases after tamoxifen is stopped. Talk with your doctor about the risks and benefits of taking this drug.

Taking raloxifene increases the risk of blood clots in the lungs and legs, but does not appear to increase the risk of endometrial cancer. In postmenopausal women with osteoporosis (decreased bone density), raloxifene lowers the risk of breast cancer for women who have a high or low risk of breast cancer. It is not known if raloxifene would have the same effect in women who do not have osteoporosis. Talk with your doctor about the risks and benefits of taking this drug.

Other SERMs are being studied in clinical trials.

Aromatase inhibitors and inactivators

Aromatase inhibitors (anastrozole, letrozole) and inactivators (exemestane) lower the risk of recurrence and of new breast cancers in women who have a history of breast cancer. Aromatase inhibitors also decrease the risk of breast cancer in women with the following conditions:

• Postmenopausal women with a personal history of breast cancer.
• Women with no personal history of breast cancer who are 60 years and older, have a history of ductal carcinoma in situ with mastectomy, or have a high risk of breast cancer based on the Gail model tool (a tool used to estimate the risk of breast cancer).

In women with an increased risk of breast cancer, taking aromatase inhibitors decreases the amount of estrogen made by the body. Before menopause, estrogen is made by the ovaries and other tissues in a woman’s body, including the brain, fat tissue, and skin. After menopause, the ovaries stop making estrogen, but the other tissues do not. Aromatase inhibitors block the action of an enzyme called aromatase, which is used to make all of the body’s estrogen. Aromatase inactivators stop the enzyme from working.

Possible harms from taking aromatase inhibitors include muscle and joint pain, osteoporosis, hot flashes, and feeling very tired.

Risk-reducing mastectomy

Some women who have a high risk of breast cancer may choose to have a risk-reducing mastectomy (the removal of both breasts when there are no signs of cancer). The risk of breast cancer is much lower in these women and most feel less anxious about their risk of breast cancer. However, it is very important to have a cancer risk assessment and counseling about the different ways to prevent breast cancer before making this decision.

Ovarian ablation

The ovaries make most of the estrogen that is made by the body. Treatments that stop or lower the amount of estrogen made by the ovaries include surgery to remove the ovaries, radiation therapy, or taking certain drugs. This is called ovarian ablation.

Premenopausal women who have a high risk of breast cancer due to certain changes in the BRCA1 and BRCA2 genes may choose to have a risk-reducing oophorectomy (the removal of both ovaries when there are no signs of cancer). This decreases the amount of estrogen made by the body and lowers the risk of breast cancer. Risk-reducing oophorectomy also lowers the risk of breast cancer in normal premenopausal women and in women with an increased risk of breast cancer due to radiation to the chest.

However, it is very important to have a cancer risk assessment and counseling before making this decision. The sudden drop in estrogen levels may cause the symptoms of menopause to begin. These include hot flashes, trouble sleeping, anxiety, and depression. Long-term effects include decreased sex drive, vaginal dryness, and decreased bone density.

Getting enough exercise

Women who exercise four or more hours a week have a lower risk of breast cancer. The effect of exercise on breast cancer risk may be greatest in premenopausal women who have normal or low body weight.

It is not clear whether the following affect the risk of breast cancer:

Hormonal contraceptives

Hormonal contraceptives contain estrogen or estrogen and progestin. Some studies have shown that women who are current or recent users of hormonal contraceptives may have a slight increase in breast cancer risk. Other studies have not shown an increased risk of breast cancer in women using hormonal contraceptives.

In one study, the risk of breast cancer slightly increased the longer a woman used hormonal contraceptives. Another study showed that the slight increase in breast cancer risk decreased over time when women stopped using hormonal contraceptives.

More studies are needed to know whether hormonal contraceptives affect a woman’s risk of breast cancer.

Environment

Studies have not proven that being exposed to certain substances in the environment, such as chemicals, increases the risk of breast cancer.

Studies have shown that some factors have little or no effect on the risk of breast cancer.

The following have little or no effect on the risk of breast cancer:

• Having an abortion.
• Making diet changes such as eating less fat or more fruits and vegetables.
• Taking vitamins, including fenretinide (a type of vitamin A).
• Cigarette smoking, both active and passive (inhaling secondhand smoke).
• Using underarm deodorant or antiperspirant.
• Taking statins (cholesterol-lowering drugs).
• Taking bisphosphonates (drugs used to treat osteoporosis and hypercalcemia) by mouth or by intravenous infusion.
• Changes in your circadian rhythm (physical, mental, and behavioral changes that are mainly affected by darkness and light in 24 hour cycles), which may be affected by working night shifts or the amount of light in your bedroom at night.

Breast Cancer Risk in American Women

What is the average American woman’s risk of developing breast cancer during her lifetime?

Based on current incidence rates, 12.8% of women born in the United States today will develop breast cancer at some time during their lives. This estimate, from the most recent SEER Cancer Statistics Review (a report published annually by the National Cancer Institute’s [NCI] Surveillance, Epidemiology, and End Results [SEER] Program), is based on breast cancer statistics for the years 2014 through 2016. 

This estimate means that, if the current incidence rate stays the same, a woman born today has about a 1 in 8 chance of being diagnosed with breast cancer at some time during her life. On the other hand, the chance that she will never have breast cancer is 87.2%, or about 7 in 8. 

For men born in the United States today, the lifetime risk of breast cancer is 0.13%, based on breast cancer statistics for the years 2014 through 2016. This means that a man born today has about a 1 in 800 chance of being diagnosed with breast cancer at some time during his life.

What is the average American woman’s risk of being diagnosed with breast cancer at different ages?

Many women are more interested in the risk of being diagnosed with breast cancer at specific ages or over specific time periods than in the risk of being diagnosed at some point during their lifetime. Estimates by decade of life are also less affected by changes in incidence and mortality rates than longer-term estimates.

The SEER report estimates the risk of developing breast cancer in 10-year age intervals. According to the current report, the risk that a woman will be diagnosed with breast cancer during the next 10 years, starting at the following ages, is as follows: 

•    Age 30 . . . . . .  0.48% (or 1 in 208)
•    Age 40 . . . . . .  1.53% (or 1 in 65)
•    Age 50 . . . . . .  2.38% (or 1 in 42)
•    Age 60 . . . . . .  3.54% (or 1 in 28)
•    Age 70 . . . . . .  4.07% (or 1 in 25)

These risks are averages for the whole population. An individual woman’s breast cancer risk may be higher or lower depending on known factors, as well as on factors that are not yet fully understood.

For more information about the risk of developing breast cancer at specific ages, within specific time periods, and for different racial/ethnic groups, and the lifetime risk of dying from breast cancer see the SEER data table.

How has the risk of being diagnosed with breast cancer changed in recent years?

For a woman born in the 1970s in the United States, the lifetime risk of being diagnosed with breast cancer, based on breast cancer statistics from that time, was just under 10% (or about 1 in 10). 

The last five annual SEER Cancer Statistics Review reports show the following estimates of lifetime risk of breast cancer, all very close to a lifetime risk of 1 in 8:

•    12.44%, based on statistics for 2013 through 2015
•    12.41%, based on statistics for 2012 through 2014
•    12.43%, based on statistics for 2011 through 2013
•    12.32%, based on statistics for 2010 through 2012
•    12.33%, based on statistics for 2009 through 2011

SEER statisticians expect some variability from year to year. Slight changes may be explained by a variety of factors, including minor changes in risk factor levels in the population, slight changes in breast cancer screening rates, or just random variability inherent in the data.