Breast Cancer

Breast cancer

This page was reviewed under our medical and editorial policy by Maurie Markman, MD, President, Medicine & Science

This page was updated on July 20, 2022.

After skin cancer, breast cancer is the second most commonly diagnosed cancer among U.S. women, affecting one in eight women who live to the age of 80. An estimated 310,720 new cases of breast cancer will be diagnosed in U.S. women in 2024, according to the American Cancer Society. Breast cancer accounts for 30 percent of all new female cancers each year.

No breast cancer patient is the same. Get personalized treatment.

At City of Hope, our experts have the training and expertise to quickly diagnose breast cancer and tailor a treatment plan to each patient’s unique needs. Our oncologists have experience with early-stage and complex breast cancers, including triple-negative and inflammatory. City of Hope patients have access to tools such as advanced genomic testing and a wide range of breast cancer treatments, including breast-conserving surgery, immunotherapy and clinical trials. Breast cancer is such an important focus at City of Hope that each of our hospitals has a Breast Cancer Center dedicated to treating patients with all stages of this complex disease.

This overview will cover the basic facts about breast cancer, including:

If you believe you may be experiencing symptoms of breast cancer and want to schedule an appointment for diagnostic testing, or if you’re interested in a second opinion for breast cancer, call us or chat online with a member of our team.

What causes breast cancer?

Who gets breast cancer?

The risk for developing breast cancer increases with age. According to the National Cancer Institute:

  • The average age of a woman diagnosed with breast cancer is 62.
  • The average age of a woman who dies from breast cancer is 68.
  • Breast cancer is the most common cancer diagnosed in women between age 55 and 64.
  • About 10 percent of breast cancers occur in women younger than 45.

Women with a family history of breast cancer may be at a higher risk for developing the disease. For example:

  • Women whose mother, sister or daughter has or had breast cancer may have double the risk.
  • Women with a brother, father or son who has or had breast cancer also have a higher risk, as do women with a first-degree relative or multiple relatives who have or had ovarian cancer.
  • Women who have inherited mutations in the BRCA1 or BRCA2 gene are at higher risk.
  • Jewish women of Ashkenazi descent are more likely to have the inherited mutations in the BRCA1 or BRCA2 genes.

Other factors that may increase a woman’s risk for developing breast cancer include:

  • Obesity
  • Breast density
  • Menstrual history
  • A sedentary lifestyle
  • Heavy drinking
  • Previous medical treatments

Race and ethnicity may also factor into a woman’s risk of developing, as well as the risk of dying, from breast cancer.

  • White women are more likely to develop breast cancer than Black women, but Black women are more likely to die from the disease.
  • Black women account for more of the breast cancer cases among women under age 45, and make up a higher percentage of triple-negative breast cancer cases (a less common type of the cancer).
  • Asian, Hispanic and Native American women are less likely to develop breast cancer or die from breast cancer than Black or white women.

Breast cancer also occurs in men but is very rare – male breast cancer accounts for 1 percent of all diagnoses. Approximately 2,800 American men will be diagnosed with breast cancer in 2024, according to the American Cancer Society.

Miriam Trejo

Miriam T.

Breast Cancer

"My experience was consistently empowering. I was part of the decision-making process at every step of the way. My care team was exactly that—a team of caring people—and I made lifelong friends with patients and employees. My naturopathic provider and my dietitian helped me manage and prevent side effects, taught me how to shop for and cook healthier foods, and recommended supplements to take during and after treatment to help my recovery."


More About MIRIAM

Breast cancer symptoms

Types of breast cancer

Breast cancers share one main thing in common—they all begin in the breast. Most breast cancers start in the ducts that carry milk to the nipple, or in the “lobules,” where breast milk is made. However, there are many different types of breast cancer, and the distinctions between them can be difficult to understand.

Breast cancer types are separated into two main groups: invasive or in situ (non-invasive). All kinds of breast cancer fall under one of these categories.

In situ (non-invasive): When breast cancer is not invasive, it is most likely ductal carcinoma in situ (DCIS), a non-invasive type of breast cancer that starts in a milk duct and has not yet spread anywhere else. DCIS accounts for approximately 1 in 5 new cases of breast cancer. DCIS is also called stage 0 breast cancer, and most women have a positive prognosis at this stage. However, DCIS can progress and spread beyond the milk ducts, becoming invasive cancer.

Invasive: Invasive breast cancer refers to any breast cancer that spreads from the original site and “invades” other areas, like nearby breast tissue, lymph nodes or anywhere else in the body. Most breast cancers are invasive.

The most common type of invasive breast cancer is called invasive ductal carcinoma (IDC). IDC accounts for roughly 70 to 80 percent of all breast cancers. IDC starts in a milk duct and spreads, growing into other parts of the breast. With time, it may spread further, or metastasize, to other parts of the body.

Invasive lobular carcinoma (ILC) is the second most common type, accounting for roughly 5 to 10 percent of all breast cancers. ILC starts in lobules—where breast milk is made—and then spreads into nearby breast tissue. Like IDC, it can metastasize.

There are many other subtypes of invasive breast cancer—some are more challenging to treat or easier to treat than the more common IDC. Other, less common types of breast cancer include:

Types of invasive breast cancers

  • Triple-negative breast cancer is an invasive breast cancer that is hard to treat. About 15 percent of all breast cancers are triple-negative breast cancer.
  • Inflammatory breast cancer is a rarer type of invasive breast cancer. Roughly 1 to 5 percent of all breast cancers are inflammatory breast cancer.

Rare breast cancers that affect other types of cells in the breast, which are more aggressive and more challenging to treat:

  • Paget’s disease of the breast accounts for about 1 to 3 percent of all breast cancers.
  • Angiosarcoma accounts for about 1 percent of all breast cancers.
  • Phyllodes tumors make up less than 1 percent of all breast tumors, and the majority of them aren’t cancerous. However, these tumors tend to fall into one of three categories: benign (non-cancerous), malignant (cancerous) or borderline (somewhere between benign and malignant).

When breast cancer spreads out of the breasts and beyond nearby lymph nodes into other parts of the body, like the bones, lungs, liver or brain, it’s called metastatic, the most advanced breast cancer stage.

Breast cancer types may also be differentiated by other factors, which help determine the treatments that are most likely to work. Your doctor will identify these factors to come up with the most appropriate treatment plan for you. These factors include:

  • Where in the breast the cancer begins: Breast cancer may start in the ducts, the lobules or elsewhere in the breast (rarely).
  • Hormone receptor status: Hormone receptor status refers to whether breast cancer cells have specific proteins that act as “receptors” and attach to the hormones estrogen and progesterone. If a patient’s breast cancer cells have hormone receptors, then the cancer is hormone receptor-positive, which means the hormones estrogen and progesterone are responsible for fueling the cancer’s growth. If there are no receptors, the cancer is hormone receptor-negative. Hormone receptor status is determined by testing breast cancer cells that are removed during a biopsy or surgery. A cancer’s hormone receptor status will influence how it’s treated.
  • HER2 status. Breast cancers can be HER2-positive or HER2-negative, depending on the levels of a growth-promoting protein called HER2 within the cancer cells.
    • HER2-positive breast cancers have high levels of the HER2 protein, which means they are more likely to be fast-growing than some other types of breast cancer, but they may also be treated with drugs specifically designed to target the HER2 protein.
    • Cancers that are HER2-negative do not respond to the same drugs.

Learn more about breast cancer types

Diagnosing breast cancer

Creating a breast cancer treatment plan

If you’ve been diagnosed with breast cancer, the next step will be to partner with your care team on treatment options. It's important to spend time learning about the benefits and risks of each approach. Your care team—which may include an oncologist, nurses, social workers and other supportive providers—is there for you to learn from and lean on.

  • Take notes about what you’ve learned, or ask a loved one to help write down questions and concerns.
  • Decide on a treatment plan jointly with your care team, when you’re ready.
  • Don’t hesitate to seek a second opinion or ask about clinical trials.
  • Consider joining a support group, where you can talk to other people who’ve also fought breast cancer.

Understanding your breast cancer treatment options

Diagnosis and treatment options at our Breast Cancer Centers

At the Breast Cancer Centers at our hospitals in Atlanta, Chicago and Phoenix, our cancer experts are devoted to a single mission—treating breast cancer patients with compassion and precision. Each patient’s care team is led by a medical oncologist and coordinated by a registered oncology nurse, who helps track the various appointments, follow up on tests and answer questions that come up along the way. Your care team also may include a breast surgeon, radiation oncologist, radiologist, pathologist and a plastic and reconstructive surgeon with advanced training in helping patients restore function and appearance. Fertility preservation and genetic testing are also available for qualifying patients who need them.

Our pathologists and oncologists are experienced and trained in tools designed to diagnose, stage and treat different types of breast cancer, from early-stage ductal carcinoma in situ to complex diseases such as triple-negative and inflammatory breast cancer.

Our breast surgeons offer microsurgical approaches such as nipple-sparing mastectomy and reconstructive flap surgery, and our radiation oncologists employ technologies designed to reduce the risk of radiation exposure to the heart and other critical organs. The Breast Cancer Center is also involved in clinical trials on precision treatments and innovative technologies, including targeted therapies. These trials may offer participants options that may have otherwise been unavailable to them.

If you believe you may be experiencing symptoms of breast cancer and want to schedule an appointment for diagnostic testing, or if you’re interested in a second opinion for breast cancer, call us or chat online with a member of our team.