Breast Cancer: Symptoms, Causes, Treatment

Written by Madeline Laguaite
Medically Reviewed by Brunilda Nazario, MD on November 14, 2023

Breast cancer is when the cells under one or both breasts grow out of control. Those cells may spread beyond your breasts and nearby lymph nodes. When that happens, the cancer is called metastatic.

Breast cancer usually begins either in your glands that make milk (a cancer called lobular carcinoma) or the ducts that carry it to the nipple (a cancer called ductal carcinoma). It can grow larger in your breast and spread to nearby lymph nodes or through your bloodstream to other organs. The cancer may grow and invade tissue around your breast, such as your skin or chest wall.

A lump under the breast, which you may or may not feel, is usually the first sign of breast cancer. When you get a mammogram, your doctor may notice this lump. You also may not notice any signs in the early stages.

The symptoms of breast cancer can include:

  • A lump or thickened area in or near your breast or underarm that lasts through 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 that can be bloody or clear
  • Changes in the skin of your breast or your nipple (It may 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 spot under your skin

Read more about the less-common signs of breast cancer.

Some of the most common types of breast cancer include in situ cancers and invasive cancers.

In situ cancers

In situ cancers 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 cancer is still in your 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 your lobules, which produce breast milk. It isn’t a “true” cancer, but it means you’re more likely to get breast cancer later. If you have it, get regular breast exams and mammograms.

Invasive cancers

Invasive cancers have spread or invaded the surrounding breast tissue.

Invasive or infiltrating ductal carcinoma (IDC). This cancer starts in your 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 your lobules but spreads to surrounding tissues or other body parts. It accounts for about 10% of invasive breast cancers. Subtypes of this invasive breast cancer include:

  • Adenoid cystic (or adenocystic) carcinoma: These are similar to 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 part of your brain called the medulla
  • 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: This rare type usually affects women who’ve been through menopause — Fingerlike projections set these tumors apart
  • Triple-negative breast cancer: This type happens when the cancer cells don’t have the right hormonal receptors and it makes up almost 15% of all breast cancers — It can happen at any age, but generally in women under 40
  • Tubular carcinoma:The tumors are slow-growing and tube-shaped

Less common types include:

  • Inflammatory breast cancer, a rare type caused by inflammatory cells in lymph vessels in your skin
  • Paget’s disease of the nipple, a type that affects the areola, the thin skin around your nipple
  • Phyllodes tumors of the breast,rare tumors grow in a leaflike pattern (They grow quickly but rarely spread outside the breast)
  • Angiosarcoma, a rare cancer that begins in blood or lymph vessels in the breast tissue or in the skin of the breast

Breast cancer epidemiology

Among women, breast cancer is the second most common cancer diagnosed, after skin cancer. It’s the second leading cause of cancer deaths, after lung cancer. About 300,000 cases of breast cancer are reported annually in the U.S.

Men can get breast cancer, too, but they account for less than 1% of all cases. About 2 in 3 women with breast cancer are 55 or older. Breast cancer will affect 1 in 8 women in their lifetimes. 

More than 40,000 Americans die of breast cancer each year, accounting for around 7% of all cancer-related deaths.

Experts don’t know what causes breast cancer, but certain things make you more likely to get it. 

Breast cancer risk factors you can’t control

Your age, genes, personal health history, and diet all play a role. Some you can control. Others you can’t.

Age. Women over 50 are more likely to get breast cancer than younger women.

Race. Black 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 go up more sharply if you’ve had breast cancer before.

Family history. If a first-degree female relative (like your mom, sister, or daughter) had breast cancer, you’re two times more likely to get the disease. Having two or more first-degree relatives with a history of breast cancer increases your risk at least three times. This is especially true if they got cancer before menopause or if it affected both breasts. The risk can also rise if your father or brother was diagnosed with breast cancer.

Genes. Changes to two genes, BRCA1 and BRCA2, are responsible for some cases of breast cancer in families. About 1 in 200 women have one of these genes. While they make you more likely to get cancer, they don’t mean you definitely 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 they’re linked to pancreatic cancer and male breast cancer. 

Other gene mutations linked to breast cancer risk include mutations of the PTEN gene, the ATM gene, 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
  • 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

Below are some breast cancer risk factors you can control. 

Physical activity. The less you move, the higher your chances.

Weight and diet. Being overweight or having obesity after menopause raises your odds.

Alcohol. Alcohol is a known carcinogen, which means it’s a cancer-causing substance. Drinking regularly — especially more than one drink a day — increases your risk of breast cancer.

Reproductive history. These things may affect your breast cancer risk:

  • You have your first child after age 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 five years — This increase in breast cancer risk returns to normal five years after you stop treatment
  • Use certain birth control methods, including birth control pills, shots, implants, IUDS, skin patches, or vaginal rings that have hormones

Still, most women who are at high risk for breast cancer don’t get it. On the other hand, 3 in 4 women who develop breast cancer have no known risk factors. 

Learn more about the risk factors for breast cancer.

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

They’ll ask about your personal and family health history. Then, they’ll do a breast exam and order tests that include:

Imaging tests. Your doctor will use these to learn more about your breast.

Ultrasound. This test uses sound waves to make a picture of your breast.

Mammogram. This detailed X-ray 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 look at it under a microscope to check for cancer cells and, if they’re there, learn which type they are. Common procedures include:

  • Fine-needle aspiration: This is for 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 nearby 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 to guide the needle

The doctor can test your biopsy sample for a variety of features.

Tumor features. Is it invasive or in situ, ductal, or lobular? 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 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 five reference genes to estimate the risk of the cancer coming back within 10 years of 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), whichmeasures 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 the way it should)
  • Blood chemistry, which shows how well your liver and kidneys are working
  • Hepatitis tests, which doctors sometimes do to check for hepatitis B and hepatitis C. 

If you have an active hepatitis B infection, you may need medication to fight the virus before you get chemotherapy. Without it, chemo can cause the virus to grow and damage your liver.

Find out more on the tests and biopsy for breast cancer diagnosis here.

Doctors use breast cancer stages based on a variety of factors.

Early stage, stage 0, or noninvasive breast cancer

This means the cancer is only in your breast, with no signs that it’s spread to your lymph nodes. Your doctor will call this carcinoma in situ.

Stage 1 breast cancer

Stage 1 breast cancer — stage I breast cancer — is 2 centimeters or less in size and hasn’t spread.

Stage 2 breast cancer

You may see stage 2 breast cancer using Roman numerals (“stage II breast cancer”). A stage 2 diagnosis can be stage 2A (IIA) or stage 2B (IIB). With stage 2A, the tumor is either

  • Smaller than 2 centimeters across, with underarm lymph node involvement
  • Larger than 2 but less than 5 centimeters across, without lymph node involvement

With stage 2B breast cancer, the tumor is either:

  • Larger than 5 centimeters across, without underarm lymph node involvement
  • Larger than 2 but less than 5 centimeters across, with lymph node involvement

Stage 3 breast cancer

Stage 3 or stage III breast cancer includes stage 3A, stage 3B, or stage 3C. Stage 3A (IIIA) breast cancer is also called locally advanced breast cancer. It’s either

  • A tumor larger than 5 centimeters that has spread to the lymph nodes under your arm or near your breastbone
  • Any size tumor with cancerous lymph nodes that stick to one another or nearby tissue

Stage 3B (IIIB) breast cancer is a tumor of any size that’s spread to your skin or chest wall.

Stage 3C (IIIC) is a tumor of any size that’s spread farther and involves more lymph nodes.

Stage 4 breast cancer or metastatic breast cancer

Stage 4 breast cancer (you may see it as “stage IV breast cancer”) is also known as metastatic breast cancer. It’s a tumor — regardless of size — that’s spread to places far away from your breast, such as your bones, lungs, liver, brain, or distant lymph nodes.

Get more information about the stages of breast cancer.

If the tests find breast cancer, you and your doctor will create a treatment plan to get rid of the cancer. This can lower the odds that it’ll come back and reduce the chance of it moving beyond your breast. Treatment generally follows within a few weeks after the diagnosis.

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

Local treatments remove, destroy, or control the cancer cells in a specific area, such as your breast. These include options like surgery and radiation.

Surgery

There are a few types of surgery to treat breast cancer.

Breast-conserving surgery. The surgeon removes only the part of your breast with the cancer, along with some nearby tissue. How much they take out depends on things like the size and location of your tumor. You might also hear it called:

  • Lumpectomy
  • Quadrantectomy
  • Partial mastectomy
  • Segmental mastectomy

Surgery to remove lymph nodes. Your doctor might take lymph nodes from under your arm to find out whether cancer has spread to them. There are two kinds of this surgery:

  • Sentinel lymph node biopsy, in which your doctor removes one or a few lymph nodes where cancer is most likely to spread
  • Axillary lymph node dissection, whichinvolves more nodes, though usually fewer than 20

Mastectomy. A surgeon removes your entire breast, along with all of the breast tissue and sometimes nearby tissues. There are several types of mastectomies:

  • Simple or total mastectomy, in which a surgeon removes your entire breast, but not the lymph nodes under your arm unless they’re within breast tissue
  • Modified radical mastectomy, in which a surgeon removes your entire breast along with lymph nodes under your arm
  • Radical mastectomy, in which a surgeon removes your entire breast and lymph nodes under your arm and up to your collarbone, as well as the chest wall muscles under your breast
  • Partial mastectomy, in which a surgeon removes the cancerous breast tissue and some tissue nearby — usually more than in a lumpectomy
  • Nipple-sparing mastectomy, in which a surgeon removes all the breast tissue but leaves your nipple alone
  • Contralateral prophylactic mastectomy, where you choose to have both breast removed, like in cases whereyou have cancer in one breast and a very high risk of getting it in the other breast

Know more about breast cancer surgery options.

Radiation

Whether you get radiation and what type will depend 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 of the following types of radiation.

External beam radiation. This type comes from a machine outside your body. You generally get it five days a week for five to six weeks. Some types of external beam radiation include:

  • Hypofractionated radiation therapy, in which youget larger doses using fewer treatments, typically only three weeks
  • Intraoperative radiation therapy (IORT), in which you get a single large dose of radiation in the operating room right after breast conservation surgery (before the wound is closed)
  • 3D-conformal radiotherapy, in which 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 five days)

Internal radiation (brachytherapy). In this type, your doctor puts something radioactive inside your body for a short time. This type can include:

  • 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. The device is widened and stays in place during the treatment. The other end sticks out of the breast. The doctor uses a tube to put radiation sources (often pellets) into the device. You usually get this twice a day for five days as an outpatient. After the last treatment, the doctor collapses the device and removes it.

Systemic treatments are another type of treatment option. They destroy or control cancer cells all over your body. These treatments include chemo, hormone therapy, and targeted therapy.

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. You may have options such as:

Targeted drugs

These drugs stop the changes that make cells grow out of control. Below are some common options.

Monoclonal antibodies, including:

Kinase inhibitors, which may include: 

CDK4/6 inhibitors, including: 

An mTOR inhibitor called everolimus (Afinitor) or a PI3K inhibitor called alpelisib (Piqray) may also be an option for you.

Gedatolisib (Revtorpyk) is a PI3K/mTOR inhibitor used with fulvestrant, with or without palbociclib, for adults with locally advanced or metastatic HR-positive, HER2-negative breast cancer without a detected PIK3CA mutation. It may be used after the cancer progresses during or after at least one endocrine therapy for metastatic disease.

The antibody-drug conjugate (ADC) datopotamab deruxtecan (Datroway) targets cancer cells that have a specific protein called TROP-2 on their surface. The antibody attaches to TROP-2 and delivers a chemo drug directly into the cancer cell, killing it. This can keep the cancer from growing and may cause it to shrink in size.

Lastly, PARP inhibitors — such as olaparib (Lynparza) or talazoparib (Talzenna) — may be a good choice.

Immunotherapy

Medications such as pembrolizumab (Keytruda) a PD-1 Inhibitor, help your immune system fight cancer.

Which treatment is best for you depends on your type of breast cancer and stage, among other factors. You and your doctor can work together to come up with a plan that works best for you.

White women in the U.S. have the highest rates of breast cancer among all races and ethnicities, just ahead of Black women. But Black women are 40% more likely to die from their breast cancers, compared to white women. This disparity stems from many factors. One reason may be that Black women on average get diagnosed with breast cancer at earlier ages, and with more aggressive types, compared to other groups. 

Asian, Hispanic, and Native American women in the U.S. have lower rates of breast cancer than both white and Black women, and also are less likely to die from it.

These tips may help you prevent breast cancer:

  1. Control your weight. Extra pounds and weight gain as an adult raise your odds for breast cancer after menopause.
  2. 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.
  3. Limit or skip alcohol. Experts recommend that women have no more than one 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). Keep in mind, there is no safe level of alcohol for your health.
  4. Breastfeed. Longer is better to lower your risk.
  5. Limit hormone therapy after menopause. Ask your doctor about non-hormonal options to treat your symptoms.
  6. Get screened. Recommendations vary by age and risk and other factors. Some of the most recent include:
    • U.S. Preventive Services Task Force:
      • 40-49: Get a mammogram every two years if you and your doctor think you need it.
      • 50-74: Get a mammogram every two 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 one to two years.
      • 75+: Get a mammogram every year so long as you’re in good health and are expected to live 10 years or more.

Management if you’re at high risk

If you have one of the risk factors for breast cancer, talk to your doctor about some things that may help lower your odds. These include:

  • Genetic testing to look for a change in your genes that raises your risk
  • More frequent doctor visits and screening tests
  • Medicines such as raloxifene, tamoxifen, and aromatase inhibitors
  • Surgery to remove your breasts or ovaries

Your outlook after breast cancer depends on many things, including your cancer stage at the time of diagnosis.

  • Nearly 99% of women whose cancer is only in their breast and hasn’t spread to other body parts live at least five years after diagnosis
  • If your breast cancer spreads to nearby lymph nodes, the five-year survival rate is closer to 86%
  • If the cancer spreads to other parts of your body — like your lungs, liver, and bones — the chance of living at least five more years is 31%.

For anyone who’s had breast cancer, there’s a chance that some breast tissue cells still in the body can start to multiply and become cancerous. The chances are different for every person. The cancer can come back in the same area (local recurrence) or in another part of your body away from the breast area (regional and distant recurrence). Even if it’s far away from the breasts, it’s still breast cancer. The signs and symptoms of recurrent breast cancer can depend on where it comes back.

Your doctor will check for signs that your cancer has come back at your follow-up exams after treatment. If it does come back, they’ll make a plan to treat it right away. It will likely be different from the type of treatment you had the first time, depending on where it is, what type it is, what specific treatments you had before, and your overall health.

Breast cancer can happen for reasons beyond your control, such as your age and genes. It can also come from factors that you can change, including keeping a healthy weight and getting recommended screening. Your actions can help to both prevent breast cancer and make it more treatable.

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