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Breast cancer

Overview of breast cancer

Breast cancer is the second most common cancer affecting American women, after skin cancer. Each year in the United States, over 300,000 women are diagnosed with breast cancer. One out of every 8 American women will develop some form of breast cancer during her lifetime.

While breast cancer can also affect men, this is very rare.

Partnering with a doctor you trust offers the best chances of finding breast cancer earlier, beginning appropriate treatment sooner, and healing. Though breast cancer is common among women, if diagnosed early, it has an over 99 percent survival rate.

Our expert oncologists at Dignity Health are here to provide personalized care for breast cancer. Find a Doctor near you.


Mammogram screening finds many breast cancers before symptoms develop. When symptoms are present, the most commonly reported one is a lump or mass in the breast tissue.

Others include:

  • Swelling in part or all of the breast
  • Skin changes on the breast or nipple
  • Inverted nipple or nipple discharge that isn’t breast milk
  • Change in size, shape, or appearance of the breast or nipple


Cancers are caused by damage to the DNA of your cells.

Many things can increase the likelihood of this damage, but experts don’t yet fully understand what causes breast cancer in some people and not others.

Research is ongoing, and scientists continue to make important discoveries, including new therapies and screening tools.


Having breast cancer means you have malignant cells in your breast tissue. Breast cancer can be classified based on the type of malignant cells and where they are located.

There are many different types of breast cancer, including:

  • Ductal carcinoma in situ (DCIS): only affects the cells lining the milk ducts.
  • Invasive ductal carcinoma: starts in the milk ducts but invades surrounding fatty breast tissue. This is the most common type of breast cancer.
  • Invasive lobular carcinoma: starts in the milk-producing glands and invades other tissues.
  • Less common types include inflammatory breast cancer, Paget disease of the nipple, Phyllodes tumor, and angiosarcoma.

In general, the more slowly the malignant cells grow, and the more localized they are, the easier the cancer will be to treat.

Risk factors

The leading risk factor for breast cancer is being a woman. Other risk factors include:

  • Age: risk increases with age
  • Race: the risk is higher for Caucasian people
  • Family or personal history of breast cancer
  • Taking hormone replacement therapies
  • Genetics: 5 to 10 percent of breast cancers are related to mutations in genes such as BRCA1 and BRCA2
  • Early menstruation (before age 12)
  • Late menopause (after age 55)
  • Dense breast tissue and other breast conditions
  • Exposure to DES (diethylstilbestrol), a synthetic form of estrogen prescribed to pregnant women in the 1940s and 1950s to prevent miscarriage
  • Previous radiation therapy in the chest area
  • Lifestyle factors such as being overweight, not exercising, and drinking alcohol


Breast cancer can’t always be avoided. However, you can take steps both to reduce your risk and to make sure that if you do develop it, you are diagnosed as soon as possible.

Many lifestyle choices can lower your risk of developing breast cancer, including:

  • Breastfeeding: the longer you breastfeed, the greater the protective effect
  • Not smoking, or quitting if you already smoke
  • Increasing physical activity
  • Avoiding pollution and exposure to radiation and other carcinogens (cancer-causing substances)
  • Maintaining a healthy weight and eating a healthy diet
  • Discussing your contraceptive and hormone therapy options with your doctor to see if limiting your use of synthetic hormones is possible
  • Reducing your alcohol intake

In addition to these steps, regular self-examination and medical screenings to check for breast cancer are some of the most important things you can do to reduce your risk.

The information contained in this article is meant for educational purposes only and should not replace advice from your healthcare provider.