Stage 4 breast cancer, also called metastatic breast cancer, has a five-year survival rate of about 31%. In contrast, earlier stages of breast cancer have a much higher five-year survival rate, nearing 99%.

However, survival rates are not absolute. Life expectancy varies significantly depending on several factors, including cancer type, how far it has spread, and how the body responds to treatment.

What is metastatic breast cancer?

Metastatic breast cancer is the most advanced form of the disease. It occurs when cancer cells spread beyond the breast and nearby lymph nodes to distant organs or tissues. Common areas of metastasis include the bones, liver, lungs, and brain.

Roughly 20% to 30% of people with earlier-stage breast cancer will eventually be diagnosed with metastatic breast cancer. For some, the disease is already at stage 4 at the time of initial diagnosis, although this is relatively rare.

how metastasis happens
Cancer cells can enter the bloodstream or lymphatic system, allowing them to travel and settle in distant organs. The reason why certain breast cancer cells prefer specific parts of the body is still not fully understood.

role of cancer type in spread
Different subtypes of breast cancer tend to spread to different areas. For example, triple-negative breast cancer frequently spreads to the lungs, while estrogen receptor (ER)–positive breast cancer is more likely to spread to the bones.

Metastatic breast cancer survival rates

Although metastatic breast cancer has no known cure, many people live with it for years with proper treatment. The five-year survival rate sits at around 31%, meaning individuals with this diagnosis are 31% as likely as the general population to live at least five years after diagnosis.

what affects survival
Several key factors influence survival outcomes:

  • age at diagnosis

  • cancer’s response to treatment

  • other medical conditions

  • breast cancer subtype (e.g., HER2-positive, triple-negative, ER-positive)

  • location and extent of spread

Someone with a single bone lesion and stable disease may live longer than someone whose cancer has spread to multiple organs and doesn’t respond to treatment.

Understanding the prognosis

Survival statistics can be misleading if taken at face value. They represent averages and include people who live much longer or much shorter than the reported time frame.

how survival rates are calculated
Most commonly cited statistics come from the National Cancer Institute’s SEER Program, which collects and analyzes cancer data. However, these numbers often reflect only a portion of patients and may not account for all cancer types or treatment advancements.

improvements in recent years
Survival for people with metastatic breast cancer has improved over time. One review showed that average life expectancy rose from 21 months in 1990 to 38 months by 2010. With new treatments, this number has likely continued to increase.

Treatment options

Although metastatic breast cancer cannot be cured, treatments can control the disease, improve symptoms, and extend life.

Available treatments include:

chemotherapy
Frequently used for metastatic triple-negative breast cancer.

immunotherapy
Helps the body’s immune system detect and destroy cancer cells.

bone-strengthening medications
Used to protect against fractures and manage bone pain.

radiation therapy
Relieves pain caused by cancer that has spread to the bones.

targeted hormone therapy
Common for hormone receptor-positive breast cancer to slow progression.

A quick review

Metastatic breast cancer has a lower survival rate than earlier stages, but it's important to understand that many factors affect life expectancy. The type of cancer, how far it has spread, and the effectiveness of treatment all play a role.

Despite its severity, advances in treatment have significantly improved the outlook for people with metastatic breast cancer. While a cure may not yet exist, therapies can manage the condition, improve quality of life, and offer hope for longer survival.