https://www.cancer.org/cancer/breast-cancer/treatment/treatment-of-breast-cancer-by-stage/treatment-of-stage-iv-advanced-breast-cancer.html

Treatment of Stage IV (Metastatic) Breast Cancer

Most women with stage IV breast cancer are treated mainly with systemic therapy. This may include hormone therapy, chemotherapy, targeted therapy, or some combination of these. Local treatments such as surgery or radiation might also be used to help prevent or treat symptoms.

Stage IV cancers have spread beyond the breast and nearby lymph nodes to other parts of the body. When breast cancer spreads, it most commonly goes to the bones, liver, and lungs. It may also spread to the brain or other organs.

Treatment options for stage IV breast cancer

For women with stage IV breast cancer, systemic (drug) therapies are the main treatments. These may include:

Hormone therapy
Chemotherapy (chemo)
Targeted drugs, such as trastuzumab (Herceptin) and pertuzumab (Perjeta)
Immunotherapy
Some combination of these

Surgery and/or radiation therapy may be useful in certain situations (see below).

Treatment can often shrink tumors (or slow their growth), improve symptoms, and help women live longer. These cancers are considered incurable.

Systemic (drug) treatments for stage IV breast cancer

Treatment often continues until the cancer starts growing again or until side effects become unacceptable. If this happens, other drugs might be tried. The types of drugs used for stage IV breast cancer depend on the hormone receptor status and the HER2 status of the cancer:

Hormone receptor-positive cancers

Women with hormone receptor-positive (estrogen receptor-positive or progesterone receptor-positive) cancers are often treated first with hormone therapy (tamoxifen or an aromatase inhibitor). This may be combined with a targeted drug such as a CDK4/6 inhibitor, everolimus or a PI3K inhibitor.

Women who haven’t yet gone through menopause are often treated with tamoxifen or with medicines that keep the ovaries from making hormones along with other drugs. Because hormone therapy can take months to work, chemo is often the first treatment for patients with serious problems from their cancer spread, such as breathing problems.

Hormone receptor-negative cancers

Chemo is the main treatment for women with hormone receptor-negative (ER-negative and PR-negative) cancers, because hormone therapy isn’t helpful for these cancers.

HER2-positive cancers

Trastuzumab (Herceptin) may help women with HER2-positive cancers live longer if it’s given along with chemo or with other medications such as hormonal therapy or other anti-HER2 drugs. Pertuzumab (Perjeta), another targeted drug, might be added as well. Another option is the targeted drug lapatinib (which may be given with certain chemotherapy drugs or hormone therapy) or ado-trastuzumab emtansine (Kadcyla).

HER2-negative cancers in women with a BRCA gene mutation

These women are typically treated with chemotherapy (and hormone therap