Breast Cancer

What Is Breast Cancer?

As in all forms of cancer, breast cancer is made of abnormal cells that have grown uncontrollably. Those cells may also travel to places in your body where they aren’t normally found. When that happens, the cancer is called metastatic.

Breast CancerBreast cancer usually begins in a small, confined area in the or glands, which produce milk (lobular carcinoma) or the ducts (ductal carcinoma), which carry it to the nipple. It can grow larger in the breast and spread through channels to nearby lymph nodes or through your bloodstream to other organs. The cancer may grow and invade tissue around the breast, such as the skin or chest wall. Different types of breast cancer grow and spread at different rates -- some take years to spread beyond the breast, while others grow and spread quickly.

Who Gets Breast Cancer?

Men can get breast cancer, too, but they account for less than 1% of all breast cancer cases. Among women, breast cancer is the most second most common cancer diagnosed in women after skin cancer and the second leading cause of cancer deaths after lung cancer.

On average, 1 in 8 women will develop breast cancer in her lifetime. About two-thirds of women with breast cancer are 55 or older. Most of the rest are between 35 and 54.

Fortunately, breast cancer is very treatable if detected early. Localized cancer (meaning it hasn’t spread outside your breast) can usually be treated successfully before the cancer spreads. A woman with localized breast cancer is about 99% as likely to live for at least 5 years after diagnosis.

Once the cancer begins to spread, treatment becomes more extensive. It can often control the disease for years. Improved screening tests and treatment options mean about 8 out of 10 women with breast cancer will survive at least 10 years after initial diagnosis.

What Are the Types of Breast Cancer?

Some of the most common types of breast cancer include:

In situ cancers: These types haven't spread past the duct or lobule where they started:

  • Ductal carcinoma in situ (DCIS): This is ductal carcinoma in its earliest stage (stage 0). In this case, the disease is still in the milk ducts. But if you don’t treat this type, it can become invasive. It’s often curable.
  • Lobular carcinoma in situ (LCIS): This is found only in the lobules, which produce breast milk. It isn't a true cancer, but a marker that means you’re more likely to get breast cancer later. If you have it, get regular breast exams and mammograms.


Invasive cancers: These have spread or invaded the surrounding breast tissue:

  • Invasive or infiltrating ductal carcinoma (IDC): This cancer starts in the milk ducts. It breaks through the wall of the duct and invades the fatty tissue of the breast. It’s the most common form, accounting for 80% of invasive cases.
  • Invasive lobular carcinoma (ILC): This cancer starts in the lobules but spreads to surrounding tissues or other body parts. It accounts for about 10% of invasive breast cancers. Subtypes of invasive breast cancer include:
    • Adenoid cystic (or adenocystic) carcinoma: These resemble cells found in your salivary glands and saliva.
    • Low-grade adenosquamous carcinoma (a type of metaplastic carcinoma): This rare tumor is usually slow growing and often mistaken for other types.
    • Medullary carcinoma: The tumors in this rare type are a soft, squishy mass that looks like the medulla in your brain.
    • Mucinous carcinoma: Tumors in this rare type float in a pool of mucin, part of the slippery, slimy stuff that makes up mucus.
    • Papillary carcinoma: Fingerlike projections set these tumors apart. This rare type usually affects women who’ve been through menopause.
    • Tubular carcinoma: The tumors are slow-growing and tube-shaped.

Less common types include:

  • Inflammatory breast cancer: This rare type is caused by inflammatory cells in lymph vessels in your skin.
  • Paget's disease of the nipple: This type affects the areola, the thin skin around your nipple.
  • Phyllodes tumors of the breast: These rare tumors grow in a leaflike pattern. They grow quickly but rarely spread outside the breast.
  • Metastatic breast cancer: Cancer that has spread to another body part, like your brain, bones, or lungs.

What Are the Symptoms of Breast Cancer?

The symptoms of breast cancer include:

  • A lump or thickened area in or near your breast or underarm that lasts throughout your period
  • A mass or lump -- even if it feels as small as a pea
  • A change in your breast’s size, shape, or curve
  • Nipple discharge -- it could be bloody or clear
  • The skin of your breast or your nipple looks or feels different -- it could be dimpled, puckered, scaly, or inflamed
  • Red skin on your breast or nipple
  • Changes in the shape or position of your nipple
  • An area that’s different from any other area on either breast
  • A hard, marble-sized area under your skin


What Are the Causes & Risk Factors for Breast Cancer?

We don’t know what causes breast cancer, but we do know certain things make you more likely to get it. Your age, genetic factors, personal health history, and diet all play a role. Some you can control; others you can’t.

Breast Cancer Risk Factors You Can’t Control

  • Age. Women over 50 are more likely to get breast cancer than younger women.
  • Race: African-American women are more likely than white women to get breast cancer before menopause.
  • Dense breasts. If your breasts have more connective tissue than fatty tissue, it can be hard to see tumors on a mammogram.
  • Personal history of cancer. Your odds go up slightly if you have certain benign breast conditions. They also go up more sharply if you had breast cancer in the past.
  • Family history. If a first-degree relative (mother, sister, daughter) had breast cancer, you’re two times more likely to get the disease. Having two or more first-degree relatives with a breast cancer history increases your risk at least threefold. This is especially true if she got cancer before menopause or if it affected both breasts. Risk can also rise if your father or brother was diagnosed with breast cancer.
  • Genes. Mutations, or changes, to two genes -- BRCA1 and BRCA2 -- are responsible for some cases of breast cancer in families. About 1woman in 200 has one of these genes. While they make you more likely to get cancer, they don’t ensure that you will. If you have a BRCA1 or BRCA2 mutation, you have a 7 in 10 chance of being diagnosed with breast cancer by age 80. These genes also raise your odds of ovarian cancer and are linked to pancreatic cancer and male breast cancer. Other gene mutations linked to breast cancer risk include mutations of the PTEN gene, the ATM gen, the TP53 gene, the CHEK2 gene, the CDH1 gene, the STK11 gene, and the PALB2 gene. These carry a lower risk for breast cancer development than the BRCA genes.
  • Menstrual history. Your breast cancer odds go up if:
    • Your periods start before age 12.
    • Your periods don’t stop until after you’re 55.
  • Radiation. If you had treatment for cancers like Hodgkin's lymphoma before age 40, you have an increased risk of breast cancer.
  • Diethylstilbestrol (DES). Doctors used this drug between 1940 and 1971 to prevent miscarriage. If you or your mother took it, your breast cancer odds go up.


Breast Cancer Risk Factors You Can Control

  • Physical activity. The less you move, the higher your chances go.
  • Weight and diet. Being overweight after menopause raises your odds.
  • Alcohol. Regular drinking -- especially more than one drink a day -- increases the risk of breast cancer.
  • Reproductive history:
    • You have your first child after 30.
    • You don’t breastfeed.
    • You don’t have a full-term pregnancy.
  • Taking hormones. Your chances can go up if you:
    • Use hormone replacement therapy that includes both estrogen and progesterone during menopause for more than 5years. This increase in breast cancer risk returns to normal 5 years after you stop treatment.
    • Use certain birth control methods including birth control pills, shots, implants, IUDS, skin patches, or vaginal rings that contain hormones.

Still, most women considered at high risk for breast cancer do not get it. On the other hand, 75% of women who develop breast cancer have no known risk factors.

How Is Breast Cancer Diagnosed?

If you feel a lump or something shows up on a mammogram, your doctor will begin the breast cancer diagnosis process.

The doctor will ask questions about your personal and family healthy history. Then they’ll do a breast exam and possibly order tests that include:

Imaging tests: Your doctor will use these to create an image of your breast:

  • Ultrasound. This test uses sound waves to make a picture of your breast.
  • Mammogram. This detailed X-ray of the breast gives doctors a better view of lumps and other problems.
  • Magnetic resonance imaging (MRI). This body scan uses a magnet linked to a computer to create detailed images of the insides of your breasts.
  • Biopsy. For this test, the doctor removes tissue or fluid from your breast. They’ll look at it under a microscope to see if cancer cells are present and if so, which type. There are two types of biopsy most often used on the breast:
    • Fine-needle aspiration: This is easy to reach lumps or those that might be filled with fluid.
    • Core-needle biopsy: This type uses a bigger needle to remove a piece of tissue.
    • Surgical (open) biopsy: A surgeon removes the entire lump along with surrounding normal breast tissue.
    • Lymph node biopsy: The doctor removes a part of the lymph nodes under your arm to see if the cancer has spread.
    • Image-guided biopsy: the doctor uses imaging, like MRI, mammography, or ultrasound, to guide the needle.


The doctor can test your biopsy sample for:

  • Tumor features. Is it invasive or in situ, ductal or lobular, and has it spread to your lymph nodes? The doctor also measures the margins or edges of the tumor and their distance from the edge of the biopsy tissue, which is which is called margin width.
  • Estrogen receptors (ER) and progesterone receptors (PR). This tells the doctor if the hormones estrogen or progesterone make your cancer grow. This affects how likely it is that your cancer will come back and what type of treatment is most likely to prevent that.
  • HER2. This test looks for the gene human epidermal growth factor receptor 2. It can help cancer grow more quickly. If your cancer is HER2-positive, targeted therapy could be a treatment option for you.
  • Grade. This tells the doctor how different the cancer cells look from healthy cells and whether they seem to be slower growing or faster growing.
  • Oncotype Dx. This test evaluates 16 cancer-related genes and 5 reference genes to estimate the risk of the cancer coming back within 10 years after diagnosis.
  • Breast Cancer Index. This test can help your doctor decide how you need endocrine therapy.
  • MammaPrint. This test uses information from 70 genes to predict the risk of the cancer coming back.
  • PAM50 (Prosigna). This test uses information from 50 genes to predict if the cancer will spread.

You might get blood tests including:

  • Complete blood count (CBC). This measures the number of different types of cells, like red and white blood cells, in your blood. It lets your doctor know if your bone marrow is working like it should.
  • Blood chemistry. This shows how well your liver and kidneys are working.
  • Hepatitis tests. These are sometimes done to check for exposure to hepatitis B and hepatitis C. If you have an active hepatitis B infection, you may need medication to suppress the virus before you get chemotherapy. Without it, chemo can cause the virus to grow and damage your liver.


What Are the Stages of Breast Cancer?

  • Early stage, stage 0, or noninvasive breast cancer. The disease is localized to the breast with no evidence of spread to the lymph nodes (your doctor will call this carcinoma in situ).
  • Stage I breast cancer. The cancer is 2 centimeters or less in size and hasn't spread anywhere.
  • Stage IIA breast cancer. The tumor is:
    • Smaller than 2 centimeters across with underarm lymph node involvement.
    • Larger than 2 but less than 5 centimeters across without lymph node involvement.
  • Stage IIB breast cancer. A tumor that’s:
    • Larger than 5 centimeters across without underarm lymph nodes that tests positive for cancer.
    • Larger than 2 but less than 5 centimeters across with lymph node involvement.
  • Stage IIIA breast cancer or locally advanced breast cancer:
    • A tumor larger than 5 centimeters that has spread to the lymph nodes under the arm or near the breastbone.
    • Any size tumor with cancerous lymph nodes that stick to one another or surrounding tissue.
  • Stage IIIB breast cancer. A tumor of any size that has spread to the skin or chest wall.
  • Stage IIIC breast cancer. A tumor of any size that has spread more extensively and involves more lymph nodes.
  • Stage IV (metastatic) breast cancer. A tumor, regardless of size, that has spread to places far away from the breast, such as bones, lungs, liver, brain, or distant lymph nodes.

What Is the Treatment for Breast Cancer?

If the tests find breast cancer, you and your doctor will develop a treatment plan to get rid of the cancer, to lower the odds that it will come back, as well as to reduce the chance of it moving to outside of your breast. Treatment generally follows within a few weeks after the diagnosis.

The type of treatment recommended will depend on the size and location of the tumor in the breast, the results of lab tests done on the cancer cells, and the stage or extent of the disease. Your doctor usually considers your age and general health as well as your feelings about the treatment options.


Breast cancer treatments can include the following:

Local: These remove, destroy, or control the cancer cells in a specific area, such as the breast. These include:


  • Breast-conserving surgery . The surgeononly removes the part of the breast with the cancer, along with some surrounding normal tissue. How much of the breast is removed depends on the size and location of the tumor and other things. You might also hear it called:
  • Lumpectomy
  • Quadrantectomy
  • Partial mastectomy
  • Segmental mastectomy
  • Mastectomy . A surgeon removes the entire breast, along with all of the breast tissue and sometimes other nearby tissues. There are several types of mastectomies:
    • Simple or total mastectomy: The surgeon removes your entire breast, but not the lymph nodes under your arm unless they’re within breast tissue.
    • Modified radical mastectomy: The surgeon removes your entire breast along with lymph nodes under your arm.
    • Radical mastectomy: The surgeon removes your entire breast, lymph nodes under your arm and up to your collarbone, as well as the chest wall muscles under your breast.
    • Partial mastectomy: The surgeon removes the cancerous breast tissue and some tissue nearby -- usually more than in a lumpectomy.
    • Nipple-sparing mastectomy: The surgeon removes all the breast tissue but leaves your nipple alone.

Radiation: Whether you get it and what type depends on the type of surgery you had, if your cancer has spread to the lymph nodes or somewhere else in your body, the size of your tumor, and sometimes, your age. You might have one type or a combination:

  • External beam radiation: This type comes from a machine outside the body. You generally get it 5 days a week for 5 to 6 weeks. Some types of external beam radiation include:
    • Hypofractionated radiation therapy: You get larger doses using fewer treatments -- typically for only 3 weeks.
    • Intraoperative radiation therapy (IORT): In this approach, you get a single large dose of radiation in the operating room right after breast conservation surgery (before the incision is closed).
    • 3D-conformal radiotherapy: You get radiation from special machines that can better aim it at the area where the tumor was. You’ll get treatments twice a day for 5 days.
  • Internal radiation (brachytherapy): In this type, the doctor places a radioactive source inside your body for a short time.
    • Interstitial brachytherapy: The doctor inserts several small, hollow tubes called catheters into the breast around the area where the cancer was. They stay in place for several days. Doctors put radioactive pellets into them for short periods every day.
    • Intracavitary brachytherapy: This is the most common type of brachytherapy for women with breast cancer. The doctor uses a small catheter to put a device inside your breast. Once in, the device is widened and stays in place during the treatment. The other end sticks out of the breast. The doctor uses to tube to put radiation sources (often pellets) into the device. You usually get this twice a day for 5 days as an outpatient. After the last treatment, the doctor collapses and removes the device.

Systemic: They destroy or control cancer cells all over your body. These treatments include:

  • Chemotherapy. You might take these drugs as pills or get them injected into a vein. It might be your main treatment if you have advanced breast cancer. Or you could get it before surgery (neoadjuvant chemotherapy) or after surgery (adjuvant chemotherapy).
  • Hormone therapy: Some cancers grow in response to certain hormones. These medications stop the hormones from attaching to cancer cells, which stops their growth.
    • Tamoxifen (Nolvadex, Soltamox, Tamoxen)
    • Fulvestrant (Faslodex)
    • Aromatase inhibitors:
      • Anastrozole (Arimidex)
      • Exemestane (Aromasin)
      • Letrozole (Femara)
  • Targeted drugs: These drugs stop the changes that make cells grow out of control.
    • Abemaciclib (Verzenio)
    • Everolimus (Afinitor)
    • Lapatinib (Tykerb)
    • Neratinib (Nerlynx)
    • Olaparib (Lynparza)
    • Palbociclib (Ibrance)
    • Pertuzumab (Perjeta)
    • Ribociclib (Kisquali)
    • Talazoparib (Talzenna)
    • Trastuzumab (Herceptin)
    • Trastuzumab emtansine (Kadcyla)


Can I Prevent Breast Cancer?

Yes. These tips can help with breast cancer prevention:

  • Control your weight. Lose weight if you need to, then stay at a healthy weight. Extra pounds and weight gain as an adult raise your odds for breast cancer after menopause.
  • Stay active: Exercise lowers your risk. Aim for 150 minutes of moderate or 75 minutes of heavy activity each week (or a mix). Spread it out during the week.
  • Limit or skip alcohol: Women should have no more than 1 alcoholic drink a day -- that’s 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof distilled spirits (hard liquor).
  • Breastfeed: The longer the better to lower your risk.
  • Limit hormone therapy after menopause. Ask your doctor about non-hormonal options to treat your symptoms.
  • Get screened: Recommendations vary by age and risk and other factors. Some of the most recent include:
    • U.S. Preventative Services Task Force:
  • 40-49: Get a mammogram every 2 years if you and your doctor think you need it.
  • 50-74: Get a mammogram every 2 years.
  • 75+: Ask your doctor if you should continue getting mammograms.
  • American Cancer Society:
    • 40-44: Get an annual mammogram if you and your doctor think you need it.
    • 45-54: Get an annual mammogram.
    • 55-74: Get a mammogram every 1-2 years.
    • 75+: Get a mammogram every year so long as you’re in good health and expected to live 10 years or more.
WebMD Medical Reference Reviewed by Laura J. Martin, MD on March 08, 2019



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