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Understanding Treatment > Treatments for Metastatic Breast Cancer

Treatments for MBC

Many treatment options exist for metastatic breast cancer (MBC). Not all tumors will respond to the same therapies. Because everyone responds differently to medication, it is not uncommon for patients to try multiple therapy options.1,2,3 The goal of any treatment for MBC is to slow the growth or spread of cancer and help you live longer.1,3,4 The following information may not include all possible side effects for treatment options in MBC.* For more information on your specific MBC treatment, talk with your doctor.

Treatment options in MBC

Type of treatment / What it does

Why or when used

How it is taken

Possible side effects*

Hormone (endocrine) therapy
Stops cancer growth that is caused by hormones.1

May be used by postmenopausal women (women who no longer get a menstrual period) and adult men with hormone receptor–positive (HR+) breast cancer.2,5

Orally (pill) or via injections, most often after surgery.

Hot flashes;
vaginal discharge,
dryness or irritation;
decreased sexual desire;
fatigue; nausea;
pain in muscles and joints.

Targeted therapy
Finds and attacks specific types of cancer cells to block growth or slow activity, while causing less harm to normal cells.1

To target CDK4/6 or mTOR proteins, which control how quickly cells grow and spread.5,6
If a BRCA1/2 mutation is present, to target PARP, the protein that allows cancer cells to repair themselves.1,3,8,9
For patients with HR+/HER2- advanced breast cancer with a PIK3CA mutation (PI3K inhibitors). 5

Subcutaneous shot (under the skin), intravenously into a vein (IV), or by mouth (pill).

High blood pressure;
bleeding or
clotting problems;
slow wound healing;
heart damage;
autoimmune reactions.

Damages the cancer cell’s DNA in order to kill the cancer cells and/or prevent them from growing and dividing.1,10

Used for many types of MBC, including HR+/HR- and HER2+/HER2-.1,11

May be given as an infusion into a vein (IV) or as an oral therapy.

Fatigue; hair loss;
easy bruising/bleeding;
infection; anemia;
appetite changes.

Also called biologic therapy or biotherapy; uses natural substances made by the body or in a laboratory to fight cancer cells and restore immune system function.15

Used to prevent the immune system from attacking normal cells and to help restore normal immune response against breast cancer cells.

Intravenously into a vein (IV) or by injection, either under the skin (subcutaneous) or into a muscle (intramuscular).

Fever; chills; weakness;
headache; nausea;
vomiting; diarrhea;
low blood pressure; rashes.

Radiation Therapy
Uses high-energy x-rays and other types of radiation to kill cancer cells.

Used to shrink or slow tumor growth; or to treat the symptoms of cancer, such as pain.15

Via special machines or devices that deliver radiation from outside your body to the breast near the site of your tumor, or sometimes given internally (brachytherapy).

Skin irritation dryness,
and color changes;
breast soreness;
breast swelling from fluid
build-up (lymphedema).

Attempts to remove cancer from the body.

Used to identify where cancer has spread, or to relieve symptoms. Depending on severity and location of the cancer, the types of surgery range from partial removal of tissue in or around the breast, to complete removal of the breast and surrounding lymph nodes or muscle tissue.16 There are also occasions when surgery is used to remove metastases (where the cancer has spread to other parts of the body) that might be producing pain/discomfort.

Operation of partial removal of the breast (sometimes involving breast reconstruction after the procedure), full removal of breast, or lymph node biopsy.

damage to tissues;
damage to organs; pain;
slow recovery of other
body functions.12

What treatment makes the most sense for me?

Biomarker testing may help your healthcare team gather as much information as possible about your specific type of breast cancer.2 Your clinical background, and stage and location of cancer, will help determine which treatment option and duration is most appropriate for you. Working with your healthcare team can help you understand what to expect – and determine what tests and treatments will be the most helpful. By talking openly with your healthcare team, you can feel more engaged in your treatment plan.2


  1. American Society of Clinical Oncology. Breast Cancer - Metastatic: Treatment Options. Accessed May 18, 2018.
  2. American Cancer Society. Hormone Therapy for Breast Cancer. cancer.html. Accessed May 18, 2018.
  3. BreastCancer.Org. Local Treatments for Distant Areas of Metastasis. Accessed May 18, 2018.National Cancer Institute.
  4. Breast cancer treatment (PDQ®)–patient version. Accessed June 26, 2019.
  5. American Society of Clinical Oncology. Biomarkers to guide treatment for early-stage breast cancer. recommendations-patients/biomarkers-guide-treatment-early-stage-breast-cancer. Accessed September 25, 2019.
  6. National Cancer Institute. Breast cancer treatment (PDQ®)–health professional version. Accessed December 2, 2016.
  7. American Cancer Society. Targeted therapy for breast cancer. cancer.html. Accessed September 24, 2019.
  8. American Cancer Society. FDA approves first pi3k inhibitor for breast cancer. Accessed December 9, 2019.
  9. Smart Patients. CDK4/6 and targeted therapy. Accessed December 9, 2019.
  10. Smart Patients. mTOR and targeted cancer therapy. Accessed December 9, 2019.
  11. Facing Our Risk of Cancer Empowered. Hereditary metastatic breast cancer. hboc/information/cancertreatment/breast-treatment/basics/hereditary-metastatic-breast- cancer.p…. Accessed December 9, 2019.
  12. PARP inhibitors. Accessed December 9, 2019.
  13. Cancer cells and chemotherapy. What is Chemotherapy? Accessed December 9, 2019.
  14. American Cancer Society. Treatment of stage IV (metastatic) breast cancer. stage/treatment-of-stage-iv-advanced-breast-cancer.html. Accessed December 9, 2019.
  15. American Society of Clinical Oncology. Breast Cancer - Metastatic: Treatment Options. Accessed May 18, 2018.
  16. American Cancer Society. Hormone Therapy for Breast Cancer. cancer.html. Accessed May 18, 2018.
  17. BreastCancer.Org. Local Treatments for Distant Areas of Metastasis. Accessed May 18, 2018.
  18. American Cancer Society. Hormone therapy for breast cancer. Cancer A-Z. cancer.html. Accessed December 19, 2019.
  19. American Cancer Society. Surgery for breast cancer. Cancer A-Z. Accessed December 19, 2019.