If your doctor has made a diagnosis of metastatic breast cancer, this means that the cancer has advanced to what’s known as stage 4.

Stage 4 breast cancer refers to cancer that’s spread beyond the breast tissue and local lymph nodes into other areas of the body.

To understand the prognosis, or outlook, for stage 4 breast cancer, it helps to know something about the process of metastasis. When cancer “metastasizes,” it has spread beyond the part of the body where it originated.

In the case of breast cancer, receiving a stage 4 diagnosis may mean the cancer has reached organs outside the breasts, like your bones or your lungs. In this article, we’ll go over what to expect when it comes to metastatic breast cancer, from prognosis to treatment.

According to the American Cancer Society (ACS), the 5-year survival rate after diagnosis for people with stage 4 breast cancer is 28 percent. This percentage is considerably lower than earlier stages. For all stages, the overall 5-year survival rate is 90 percent.

Because survival rates are higher in the early stages of breast cancer, early diagnosis and treatment is crucial. But remember: The right treatment for stage 4 breast cancer can improve quality of life and longevity.

Metastatic breast cancer isn’t the same for everyone who has it. According to the National Breast Cancer Foundation, your symptoms at stage 4 will depend on the degree to which the cancer has spread in your body.

Although metastatic breast cancer has no current cure, it can be treated. Getting the right treatment can increase both your quality of life and longevity.

Life expectancy for breast cancer is based on studies of many people with the condition. These statistics can’t predict your personal outcome — each person’s outlook is different.

The following factors can affect your life expectancy with metastatic breast cancer:

  • your age
  • your general health
  • hormone receptors and HER2 receptors on cells with cancer
  • the types of tissue that the cancer has affected

The symptoms of stage 4 breast cancer depend on the location of the cancer and where it has spread in your body.

  • If breast cancer has spread to your bones, you may notice a sudden new bone pain. Breast cancer most commonly spreads to your ribs, spine, pelvis, or arm and leg bones.
  • If it has spread to your brain, you may experience headaches, vision or speech changes, or memory problems.
  • Breast cancer that has spread to your lungs or liver usually causes no symptoms.

The main treatments for stage 4 breast cancer are targeted drug (systemic) therapies that destroy cancer cells wherever they are in your body.

These treatments may include:

  • hormone therapy, which stops or slows the growth of tumors by preventing your body from producing hormones or interfering with the effect of hormones on breast cancer cells
  • chemotherapy, where drugs given orally or through an IV travel through your bloodstream to fight cancer cells
  • immunotherapy, which uses drugs that stimulate your immune system to destroy cancer cells
  • a combination of these therapies

In some cases, surgery or radiation therapy may be used to treat stage 4 breast cancer.

The following are the common treatment options for different types of stage 4 breast cancer.

Hormone receptor-positive cancers

This type of cancer has cells with estrogen receptors, which are proteins that can attach to some substances in your blood, that are known as ER-positive (or ER+). It may instead have cancer cells with progesterone receptors called PR-positive (PR+), or it may have both.

Hormone receptor-positive breast cancer is usually treated with hormone therapy drugs that block estrogen receptors (like Tamoflexin) or that lower estrogen levels (aromatase inhibitors like letrozole) in your body.

Hormone receptor-negative cancers

This type of stage 4 breast cancer doesn’t have ER+ or PR+ receptors, so hormone therapy drugs don’t work.

Chemotherapy may be more effective for hormone receptor-negative breast cancer than for hormone receptor-positive breast cancer.

HER2-positive cancers

Human epidermal growth factor receptor 2 (HER2) is a protein on the surface of breast cells. With HER2-positive breast cancer, there are abnormally high levels of HER2 proteins, causing cancer cells to quickly grow and spread.

Along with chemotherapy, this type of stage 4 breast cancer is often treated with the targeted drug trastuzumab (Herceptin), a manmade antibody that attaches to the HER2 protein on cancer cells and prevents it from growing. These drugs are given by IV infusion.

HER2-negative cancers in women with a BRCA gene mutation

HER2-negative breast cancer doesn’t have a high amount of HER2 proteins. A BRCA (an abbreviation for BReast CAncer) gene mutation is caused by damage to the DNA that makes up the gene.

With a mutation, the gene can no longer suppress growth of cells with damaged DNA. This results in the gene no longer being as effective at preventing breast cancer.

In 2018, the FDA approved the oral drug olaparib (Lynparza) for treating metastasized HER2-negative breast cancer in women with a BRCA gene mutation.

HER2-negative cancers in women with a PIK3CA gene mutation

The PIK3CA gene produces the protein p110 alpha (p110α), which is essential for cell growth and other important functions. If this gene is mutated, cells may replicate uncontrollably, causing various cancers. This includes breast cancer.

Chemotherapy may not be effective for HER2-negative stage 4 breast cancer in women with a PIK3CA gene mutation because they’re less sensitive to chemotherapy drugs.

The FDA approved the oral drug alpelisib (Piqray) in 2019 for treating this specific type of breast cancer. Alpelisib is a “PI3K inhibitor” that should be administered in combination with the hormone treatment fulvestrant (Faslodex).

Triple negative breast cancer

With this type of breast cancer, the breast cancer cells don’t have ER+ or PR+ receptors. They don’t overproduce the HER2 protein, so hormone therapy isn’t very effective.

Instead, triple negative stage 4 breast cancer is usually treated with chemotherapy. Radiation therapy may also be an option, depending on the site of metastasis.

There’s currently no cure for stage 4 breast cancer, but with treatments it can be kept under control, often for years at a time.

People with metastatic breast cancer need to receive treatments for the rest of their lives. If a certain treatment stops being effective, another treatment regimen may be tried.

Stage 4 breast cancer can go into remission, meaning that it isn’t detected in imaging or other tests. Pathological complete remission (pCR) indicates a lack of cancer cells in tissues removed after surgery or biopsy.

But it’s rare to take tissue samples while treating stage 4 breast cancer. This could mean that although treatment has been effective, it hasn’t completely destroyed the cancer.

Advances in stage 4 breast cancer treatments are helping to increase the length of remission.

Metastatic breast cancer is considered a chronic disease, so it doesn’t go away and recur.

But in recent years, people under age 50 have seen a particularly strong decline in death rates due to breast cancer, according to the Centers for Disease Control and Prevention (CDC).

These declines are due in part to improved screening and treatment for the disease.

There are a few general facts that are helpful to know about breast cancer outlook:

  • Breast cancer is the most common cancer diagnosis in the United States, according to the National Cancer Institute (NCI).
  • Many people with breast cancer live longer than they used to. Over time, the number of deaths from breast cancer has dropped substantially.
  • The American Cancer Society estimates approximately 281,550 new diagnoses of breast cancer in 2021.

The stage of your breast cancer at diagnosis plays an important role in your outlook.

According to the NCI, you have the best outlook in the 5 years after your breast cancer diagnosis when the cancer is diagnosed and treated at an earlier stage.

Remember that everyone is different, and your response to treatment may not match someone else’s — even at stage 4. Researchers continue to test different treatment options for metastatic breast cancer. Each year the outlook improves.

Talk with your doctor to learn more about the individual factors that may affect your outlook.

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