Overview of Stage 4 Breast Cancer

Diagnosis, Survival, Treatment, and Coping

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Stage 4 is the most advanced form of breast cancer. It is also referred to as metastatic breast cancer because the malignancy will have spread (metastasized) from breast to other organs in the body. Metastatic disease can occur in bones, lungs, liver, brain, and nearly any other organ of the body. Stage 4 breast cancer is often diagnosed when the cancer recurs, although it may sometime be discovered at the initial diagnosis. Treatment involves controlling the spread of malignancy and promoting a good quality of life. While metastatic breast cancer is not curable, it is treatable, and there are even long-term survivors of the disease.


Stage 4 breast cancer is diagnosed when cells from a primary tumor in the breast migrate to other parts of the body and establish one or more secondary tumors. The location of these metastases can vary but tend to follow a similar pattern based on the cancer type. For example:

Different cancers also metastasize at different times and speeds. For example, estrogen receptor-positive tumors tend to be around 3 centimeters (1.2 inches) in diameter before they metastasize. By contrast, HER2-positive tumor may be less than 1 centimeter (0.4 inches) before they disseminate to lymph nodes and beyond.

For the purpose of classification and treatment, breast cancer that has spread to other parts of the body is still considered breast cancer irrespective of its location.

Breast cancer that spread to the lungs, for example, would not be referred to as lung cancer. Rather, it would be described as "breast cancer metastatic to the lungs." If you look at these cells under the microscope, they would be breast cancer cells rather than lung cancer cells.

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Cancer staging is performed to direct treatment and predict the likely outcome (known as the prognosis). The staging system most commonly used for breast cancer—and most other cancers for that matter—is called the TNM Classification of Malignant Tumors. In the TNM staging system:

  • "T" refers to tumor size
  • "N" refers to the number of lymph nodes affected by cancer
  • "M" refers to metastasis

The letters would be followed by numbers to either characterize the size of the tumor (for example, "T1" for a small tumor and "T3" for a bigger tumor) or the extent of a malignancy (with "N0" meaning no affected lymph nodes and "N4" meaning 10 or more affected lymph nodes).

With regards to the "M" classification, you can either be "M0" (no metastasis) or "M1" (metastasis). There are no in-betweens. Therefore, you can be any "T" or "N" classification and still be considered stage 4 if metastasis is confirmed.

This doesn't mean that all metastatic breast cancers are treated the same. The diagnosis would also include an assessment of the tumor location, tumor grade, tumor size, hormone receptor status, HER2 status, and many other factors, each of which directs the ultimate course of treatment.

Survival Rates

The 5-year survival rate for stage 4 breast cancer is 27 percent, according to surveillance from the National Cancer Institute. What this means is that 27 percent of women will live for at least five years. Some will live far longer, while others will live less. To this end, the median life expectancy (meaning the middle value of the reported ranges) is 3 years.

As distressing as this may seem, the figures do not differentiate between the number of women who decide to be treated versus those who don't. As such, you should not assume that having stage 4 breast means that you have 3 to 5 years to live. Some women will live in excess of 10 years.

A number of factors are known to influence survival, including:

  • Age
  • Health at the time of the diagnosis
  • Cancer stage at the time of diagnosis
  • Location and extent of the metastases
  • HER2 or hormone-receptor status
  • Whether the cancer has recurred
  • Treatments previously used

It is important to remember that survival statistics are derived from a large population of women, each of whom has distinct circumstances. Moreover, as newer and more effective treatments are being developed and released, the 5-year survival rate today may be very different than those issued five years from now.


The general aim of stage 4 cancer treatment is to limit the progression of cancer with the least amount of treatment possible. Each case will be treated differently based on the prognosis and the intended goals of treatment.

The goals can vary from one person the next. Some will opt for treatments based on the side effects and likely outcomes; others may choose palliative care to maintain the optimal quality of life. There are no "right" choices, only appropriate ones.

Systemic Therapy

For those who decide to pursue treatment, systemic therapies (those that disperse treatment throughout the body) are commonly used. These include:

A combination of therapies may be used, either together or in stages.

Treatment staging involves using a drug until the side effects are intolerable or the cancer starts to grow again. If this happens, the first-line drug will be switched a second-line drug and so on.

Drug Selection

The choice of systemic therapy is largely based on the hormone-receptor status and/or HER2 status. The hormone-receptor status is an indication of whether the hormone estrogen or progesterone affects the growth of a tumor. The HER2 status indicates whether a protein hEGF influences tumor growth.

A "positive" status means that receptors for these substances have been detected on cancer cells, while "negative" means that no receptors were found. Cancer cells obtained through biopsy or surgery are used by pathologists to determine the status.

Based on these evaluations, the oncologist will typically recommend the following treatments:

  • Hormone receptor-positive cancers are often treated with hormone therapy, such as tamoxifen or an aromatase inhibitor. This may be combined with a targeted drug such as Afinitor (everolimus), Ibrance (palbociclib), Kisqali (ribociclib), or Verzenzio (abemaciclib).
  • Hormone receptor-negative cancers are typically treated with chemo.
  • HER2-positive cancers may benefit from the targeted drug Herceptin when used in combination with chemo, hormonal therapy, or other HER2 medications.
  • HER2-negative cancers are typically treated with chemo. Hormone therapy may be added if the cancer is hormone receptor-positive. The targeted drug Lynparza (olaparib) is sometimes staged after chemo for people with BRCA1 or BRCA2 gene mutations.

Radiation and Surgery

In addition to systemic therapies, radiation and surgery may be helpful in specific circumstances. With radiation especially, the goal may be therapeutic (to slow the progression of the disease) or palliative (to provide comfort by reducing the tumor size). Among the examples:

Radiation can also shrink tumors that have penetrated the skin and caused an open wound on the breast or chest.


While the goal of early-stage cancer treatment is to eradicate the malignancy and sustain remission, the goals associated with stage 4 cancer are different. The primary aim to keep the cancer from spreading, which requires ongoing monitoring.

The tool most commonly used for this is an imaging technique known as the positron emission tomography/computed tomography (PET/CT) (PET/CT) scan. It involves PET technology, which looks at metabolic changes in the body, and CT technology, which uses X-ray to create cross-sectional images of tissue (to measure tumor size and disease progression).

Other techniques, like magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DEXA), may be used to monitor certain soft tissue or bone malignancies, respectively.

Serial blood tumor markers will also be used to monitor disease status. These are blood tests that detect substances, referred to as tumor markers, that increase as cancer either spreads or advances. Examples include the tumor markers CA 15-3 and CA 27-29 which are elevated in over 70 percent of metastatic breast cancer cases.

The Future

While systemic treatment may keep the cancer stable for months or years, there may be times when it becomes unstable and starts to progress. When this happens, a change of treatment can often stabilize the malignancy.

Generally speaking, doctors will start with hormonal therapy (if hormone receptor-positive) or targeted therapy (if HER2-positive), changing individual agents if one starts to fail.

If these no longer work, chemotherapy will be used. However, each time that cancer progresses during chemo, the chances of the new drug working progressively decreases. It is at this stage that palliative care made be considered.

Because current treatments are unlikely to cure metastatic breast cancer, you may want to take part in a clinical trial to try newer treatments if you are in good health.

A Word From Verywell

It is natural to feel depressed, anxious, or even angry when you have been diagnosed with stage 4 breast cancer. It can leave you feeling as if you have no control over your health or future. Moreover, you may find that certain people will withdraw from you or suggest that you have metastatic cancer because you "left it too late."

It is important to isolate yourself from these negative emotions and embrace those who can provide you with genuine support. These include loved ones, support groups, and your oncology team. If you are unable to cope, ask for a referral to a therapist who can provide you counseling or a psychiatrist able to dispense treatment.

With that being said, there are women who experience positive emotional growth after being diagnosed with stage 4 breast cancer. It is not uncommon to hear someone say that cancer helped prioritize their lives, allowing them to pursue what is truly important and connect with people on a deeper, more profound level.

Whatever your experience, don't go it alone. Seek support and work with your medical team as a full partner in your care. By doing so, you may no longer feel out of control.

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