Breast Cancer Overview

One in eight women in the US will develop breast cancer in her lifetime. If you or someone you love have recently been diagnosed with breast cancer, here is everything you need to know, from how to cope with your diagnosis, to how to understand all your treatment options, to inspiring patient stories.

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What is breast cancer?

As with any cancer, abnormal cells begin to divide, grow, and threaten surrounding tissue. When this process originates in the breast, it's known as breast cancer. Most breast cancers originate either in the milk-producing glands of the breast (called lobules) or the tube-shaped ducts that carry milk from the lobules to the nipple. Cancers that begin in the breast's fatty and fibrous connective tissue are less common. Often, abnormal cells cluster together, forming a tumor.

While breast cancer is much more common in women, men can develop breast cancer too.

It might begin as a lump you feel in your breast, an inverted nipple, skin thickening, or whitish specks on a mammogram. (Are all these signs the same in men?) Next thing you know, you have breast cancer. A weighty diagnosis like that can take time to process. After skin cancer, it's the most common cancer in women. Those who are newly diagnosed may grapple with what it means for their health and everyday living.

The good news is that with earlier diagnosis and better treatments, chances of recovery are better than ever. Treatment regimens are much more personalized than they used to be, and they may or may not involve chemotherapy. Even women whose breast cancer has spread to another part of the body are living longer. Men, however, have lower overall survival rates compared to women. Fewer than 1% of breast cancers occur in males, but their death rates are higher at every stage of the disease than females, and researchers are trying to figure out why.


There are many types of breast cancer and several ways to categorize them. Common breast cancers include:

  • Ductal carcinoma in situ (DCIS), an early-stage, non-invasive breast cancer.
  • Invasive ductal carcinoma (IDC), a cancer that originates in the cells lining a milk duct in the breast. It's the most common type of breast cancer.
  • Invasive lobular carcinoma (ILC), a cancer that begins in the milk-producing lobules.

Some breast cancers are rare. Inflammatory breast cancer (IBC), for example, is an uncommon-but-aggressive form, one that tends to occur in women younger than 40.

Breast cancers are also classified by their stage. Tumor staging is based on seven key characteristics:

  • Tumor size
  • Lymph node status (number and location of lymph nodes affected)
  • Metastasis (spread to other organs)
  • Tumor grade (how the tumor cells compare with the normal cells)
  • Estrogen-receptor status
  • Progesterone-receptor status
  • HER2 (human epidermal growth factor receptor 2) status


Breast cancer symptoms vary, and some people may have no symptoms at all, especially early in the disease. That's why regular screening mammograms are so important. These scans may detect small tumors before you can feel them. Still, mammography isn't foolproof, so you should also become familiar with your breasts, so you know what's normal for you and what's not. Pay attention to any breast changes you experience, including these possible warnings signs:

  • A new lump in the breast or armpit
  • A change in the size or shape of the breast (swelling, thickening, or shrinkage—especially in one breast)
  • Skin dimpling or pitting (like an orange peel)
  • Red, dry, flaking, or thickened nipple or breast skin
  • Breast or nipple pain
  • A nipple that pulls or turns inward
  • Nipple discharge
  • Swollen lymph nodes under the arm or around the collarbone


Breast cancer begins when mutated cells in the breast divide and grow with abandon. These abnormal cells form a mass of tissue called a tumor. So why do normal breast cells mutate? Sometimes inherited gene mutations (passed down through families) can lead to breast cancer. More often, DNA damage is sustained at some point during a person's life, perhaps due to lifestyle or environmental factors.

Many breast cancer risk factors are out of your control. These include:

  • Being a woman.
  • Having dense breasts.
  • Inheriting certain genes (such as BRCA1 and BRCA2).
  • Having a personal or family history of breast cancer.
  • Having an early first period (before age 12) or later menopause (after age 55).
  • Having a benign breast condition.
  • Having chest radiation.
  • Being exposed to the drug DES (short for diethylstilbestrol, a synthetic estrogen).

Other risk factors may be modifiable, such as:

  • Drinking alcohol (the more you drink, the higher the risk).
  • Being overweight or obese.
  • Being sedentary.
  • Not having children.
  • Not breastfeeding.
  • Using hormonal birth control.
  • Using hormone therapy after menopause.

Having one of these risk factors does not necessary mean that you will get breast cancer.


Doctors may use different tests and procedures to diagnose breast cancer. Women aged 45-54 should get mammograms yearly, but you can start getting tested as early as 40. Common diagnostics include:

  • Physical exam and health history
  • Breast exam
  • Mammogram
  • Ultrasound
  • MRI
  • Biopsy

Once a diagnosis is confirmed, additional tests and procedures may be performed to determine the stage of the disease and identify features of your particular cancer that may help guide treatment. These may include:

  • Additional imaging tests
  • Blood tests
  • Bone scan
  • Lab testing to measure estrogen and progesterone receptors
  • Lab testing to look for the HER2 gene and HER2 protein
  • Multigene testing to identify gene mutations linked to a higher breast cancer risk (BRCA1, BRCA2, PALB2)


Breast cancer treatment differs by the type of cancer; its size, stage, and sensitivity to hormones; a person's age and health; and other factors. If you have breast cancer, you may receive one or more of the following therapies:

Surgery: You might have breast-conserving surgery (such as lumpectomy) or a mastectomy.

Radiation therapy: Options include external beam radiation and brachytherapy.

Chemotherapy: Administered before or after surgery or as the main treatment. (Not everyone requires chemo.)

Hormone therapy: These drugs treat hormone-sensitive tumors. Tamoxifen, for example blocks estrogen receptors on breast cancer cells.

Targeted therapy: These drugs target cancer-cell features. Herceptin is one that targets HER2-positive breast cancers.

Immunotherapy: Medicines that coax the immune system to attack cancer cells, including so-called immune checkpoint inhibitors.


There's no sure way to prevent breast cancer. But there is a lot you can do lifestyle-wise to lower your risk:

  • Maintain a healthy weight: Being overweight can increase your breast cancer risk.
  • Exercise regularly: Being physically active can lower your risk of breast cancer. You'll want to aim for a minimum of 150 to 300 minutes of moderate-intensity or 75 to 150 minutes of vigorous-intensity exercise each week.
  • Limit your alcohol intake: Alcohol can be a risk factor for breast cancer in women; it's best to limit your alcohol intake to no more than one drink per day.
  • Get mammograms as recommended by your doctor: Women ages 45 to 54 are recommended to get mammograms each year; women ages 55 and older can get mammograms once every two years.
  • Perform regular self exams: Becoming familiar with your breasts can help you notice any changes, which you should then report to your doctor.
  • Consider non-hormonal options to treat menopause symptoms: Using hormone therapy after menopause may increase your risk of developing breast cancer.
  • Consider breastfeeding: Women who are able or choose to breastfeed after giving birth may decrease their risk of breast cancer.

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