Treating Different Types of Breast Cancer

Breast cancer is a term that describes any cancer that begins in the breast cells. However, there is much variation between different kinds of breast cancer. These different subtypes play an important role in determining treatment decisions.1,2

Advanced breast cancer (ABC) treatment can be complex. Finding the right treatment for each person may require trying several options before discovering what works best for that person. The overall management of advanced breast cancer is often complex and may require care from multiple specialists.1,2

Testing breast cancer for receptors

A biopsy is used to confirm a diagnosis of breast cancer. This is when a sample of tissue is removed from the body to be examined under a microscope. Biopsies are also important in people who have experienced a recurrence of breast cancer. Cancers that come back may have changed and evolved over time. It is important to test biopsy samples to see if they have these receptors on the surface of the cancer cells:2

  • Human epidermal growth factor receptor 2 (HER2)
  • Hormone receptors (HR), including estrogen receptors (ER) and progesterone receptors (PR)

Some breast cancers are classified as “triple-negative.” This means the test results are negative for all of the above receptors. There are limited targeted treatments for people with these triple-negative breast cancers, but there are other treatment options. Triple-negative breast cancers tend to be aggressive, meaning they can grow and spread quickly.2

Figure. Treatment options by subtype

Treatment pathways for hormone, targeted therapy, and chemotherapy shown, based on the biopsy and known genetic markers.

Hormone therapy

Hormone therapy, also called endocrine therapy, is used in women who have breast cancers that are hormone receptor-positive (ER+ or PR+). In ER+/PR+ breast cancers, blocking the hormones can help stop or slow cancer from growing and spreading.2

However, breast cancers can develop resistance to hormone therapy. This means the treatment no longer is effective in slowing cancer. Newer treatments help fight hormone resistance, including using a combination of targeted treatments and hormone therapy.2

Targeted therapy

Targeted therapy works to stop or slow the spread of cancer by interfering with specific areas of cancer cells that are involved in their growth processes. Several targeted therapies are used to treat certain breast cancers, including those that target:1

  • HER2+
  • CDK 4/6 (cyclin-dependent kinase 4/6)
  • PARP (poly (ADP-ribose) polymerase)
  • mTOR (mammalian target of rapamycin)
  • PI3K inhibitors
  • Antibody-drug conjugates

Immunotherapy

Immunotherapy is a type of treatment that aims to boost the immune system to fight cancer. Immunotherapies are a type of biologic therapy. Biologics are drugs made from living cells. These cells can come from parts of the blood, proteins, viruses, or tissue. This process turns the cells into drugs that can prevent, treat, and cure disease. Several types of immunotherapy are being studied or have been approved for the treatment of advanced breast cancer, including:4

  • Monoclonal antibodies
  • Adoptive cell transfer

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. Chemotherapy drugs work by targeting rapidly dividing cells, like cancer cells. The choice to use chemotherapy drugs in someone with metastatic breast cancer depends on several factors, including previous chemotherapy treatment. In general, monotherapy (use of 1 chemotherapy drug) is used to treat metastatic breast cancer, rather than combinations of drugs. However, the choice of chemotherapy drug(s) is based on each person's breast cancer and condition.1

Surgery

Regardless of the subtype, surgery may be used to treat ABC. Surgery may not be an option for certain cases of ABC. Or, surgery may only be an option after other treatment, like chemotherapy, has shrunk the tumor. Surgery options include breast-conserving treatment (lumpectomy) or surgical removal of the breast (mastectomy).3

Symptom management

All people with ABC can benefit from symptom management. This is also known as supportive or palliative care. Palliative care can improve a person’s quality of life by addressing:5

Advanced or metastatic clinical trials

People with advanced or metastatic breast cancer can also consider clinical trials. There are different types of clinical trials, including some offering new treatments that are not currently available to the general public. Talk to your doctor about the possibility of participating in a clinical trial and if clinical trials are a good option for your unique case.

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Written by: Emily Downward | Last reviewed: February 2021