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, and the different subtypes play an important role in determining treatment decisions. The treatment of advanced breast cancer can be complex and finding the right treatment for the individual may require trying multiple options before discovering what works best for that person. The overall management of advanced breast cancer (ABC) is often complex and may require the collaboration and expertise of multiple specialists.1,2

Testing breast cancer for receptors

A biopsy, in which a sample of tissue is removed from the body to be examined under a microscope, is used to confirm a diagnosis of breast cancer. Biopsies are important in women who have experienced a recurrence of breast cancer, too. Cancers that come back may have changed and evolved over time, and it’s important to test the biopsy samples to determine if they have any of the following receptors on the surface of the cancer cells2:

  • 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,” as the test results come back negative for all of the above receptors. There are limited targeted treatments that can be used in certain patients with these triple-negative breast cancers, but there are other treatment options as well. 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 breast cancers that are ER+/PR+, blocking the hormones can help stop or slow cancer from growing and spreading. However, breast cancers can develop resistance to endocrine therapy, meaning the treatment no longer is effective in slowing cancer. Newer treatments have been developed to help combat endocrine resistance, including potentially using a combination of targeted treatments and hormone therapy.2

Targeted therapy

Targeted therapy is a type of cancer treatment that stops or slows the spread of cancer by interfering with specific areas of cancer cells that are involved in the cancer cell’s growth processes. There are various targeted therapies used for the treatment of certain early-stage, advanced, and/or metastatic breast cancers, including those which target HER2+, CDK 4/6 (cyclin-dependent kinase 4/6), PARP (poly (ADP-ribose) polymerase), mTOR (mammalian target of rapamycin), PI3K inhibitors and antibody-drug conjugates.1


Immunotherapy is a type of systemic treatment (treating the whole body) that aims to boost the individual’s own immune system to fight cancer. Immunotherapies are a type of biologic therapy, as they are made from substances produced from organisms that are alive. There are several types of immunotherapy that are currently being studied or are approved for the treatment of advanced breast cancer, including4:

  • Monoclonal antibodies
  • Adoptive cell transfer


Chemotherapy is the use of drugs to kill cancer (malignant) cells. Chemotherapy drugs work by targeting rapidly dividing cells, like cancer cells. The choice of chemotherapy drugs in someone with metastatic breast cancer will depend on several factors, including previous chemotherapy treatment. In general, monotherapy (use of one single chemotherapy agent) is preferred in treating metastatic breast cancer, rather than combinations of drugs. However, the choice of chemotherapy agent(s) is based on the individual’s breast cancer and condition.1


Regardless of the subtype, surgery may be used to treat ABC. Certain cases of ABC may be considered inoperable, or surgery may only be an option after other treatment, like chemotherapy, has shrunk the tumor. Surgery options include breast-conserving treatment (lumpectomy) or mastectomy (surgical removal of the breast).3 Surgery may also be used to treat certain metastases, such as certain metastases to the brain.1

Symptom management

In addition to the treatment options mentioned above, women with ABC can benefit from symptom management, also known as supportive care or palliative care. Palliative care can improve a person’s quality of life by addressing the side effects of treatment, symptoms of the disease, and emotional and spiritual support.5

Advanced or metastatic clinical trials

In addition to the treatment options mentioned above, women with advanced or metastatic breast cancer can also consider clinical trials. There are different types of clinical trials, including some which offer new treatments that aren’t currently available to the general public. Women should talk to their doctor about the possibility of participating in a clinical trial and if clinical trials are a good option for their unique case.

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Written by: Emily Downward | Last reviewed: October 2020.