Metastatic breast cancer, also known as stage IV or advanced breast cancer, occurs when cancer cells spread beyond the breast and nearby lymph nodes to distant parts of the body—most commonly the bones, lungs, liver, brain, and regional lymph nodes. This stage can develop years after the initial breast cancer diagnosis or, in some cases, be detected simultaneously or even before the primary tumor.
How Metastatic Breast Cancer Spreads and Why It’s Challenging to Treat
Unlike earlier stages, metastatic breast cancer is not curable, though it can often be treated and managed for years. The cancer cells at this stage usually differ biologically from the original tumor, often becoming resistant to prior treatments and gaining the ability to invade other organs. These distant metastases are responsible for around 90% of breast cancer-related deaths.
Treatment for metastatic breast cancer varies depending on where the cancer has spread and may include surgery, radiation, chemotherapy, hormonal therapies, and biological agents. The spread of cancer involves overcoming various environmental barriers such as the basement membrane, oxidative stress, immune defenses, and changes in pH levels. Organ-specific factors also play a role; for example, cancer cells may follow certain blood flow patterns or respond to signals from specific organs.
This “homing” mechanism involves interactions between attractant molecules from target tissues and specific receptors on the tumor cells, influencing where the cancer cells are likely to settle and grow.
Symptoms of Metastatic Breast Cancer
The symptoms of metastatic breast cancer vary depending on where the cancer has spread. Common sites include the bones (especially the spine), lungs, liver, and, in some cases—particularly in triple-negative or HER2-positive breast cancers—the brain.
People who have been previously treated for breast cancer should stay alert to the following signs:
If the cancer has spread to the bones:
- Persistent, unexplained back or neck pain
- General bone pain without injury or strain
If the cancer has spread to the lungs:
- Unexplained shortness of breath
- Chronic or new cough
If the cancer has spread to the liver:
- Persistent fatigue or general feelings of illness (malaise)
If the cancer has spread to the brain:
- Headaches
- Seizures
- Mood or personality changes
- Difficulty speaking
- Vision problems
Keeping up with regular follow-up appointments with your primary care doctor, oncologist, and surgeon is vital. Staying proactive can help detect changes early and guide timely treatment decisions.
How Is Metastatic Breast Cancer Diagnosed?
Metastatic breast cancer is typically diagnosed based on symptoms or through follow-up evaluations. Here’s how the process usually works:
- Symptom-Based Diagnosis
If a person previously treated for breast cancer experiences new or unusual symptoms (e.g., bone pain, shortness of breath, or fatigue), doctors may investigate whether the cancer has returned or spread. - Staging Workup for New Diagnoses
For newly diagnosed patients with Stage 2 or Stage 3 breast cancer, doctors conduct a staging workup to check if the cancer has moved beyond the breast and nearby lymph nodes. This often involves imaging tests. - Early-Stage Considerations
Even in Stage 1 breast cancer, if cancer cells are found in blood vessels or lymph nodes, additional scans might be recommended to rule out metastasis. - Common Diagnostic Tests
To confirm MBC, physicians may order:- Blood tests
- Imaging scans (CT, PET, MRI, or bone scans)
- Biopsies of any suspicious areas
Regular monitoring and prompt reporting of new symptoms play a crucial role in early detection and effective treatment planning.
Where Can Metastatic Breast Cancer Spread?
It means the cancer has spread beyond the breast to other parts of the body. While it can spread almost anywhere, some areas are more commonly affected. That’s why it’s important to tell your doctor about any new or unusual pain or symptoms, no matter where they occur.
Common Areas Where Breast Cancer Spreads
1. Bones
- Common sites: Spine, ribs, pelvis, arms, and legs.
- Symptoms: New or sudden bone pain, especially in these areas.
2. Brain
- Symptoms: Headaches, nausea or vomiting, trouble with balance, vision or speech changes, and memory issues.
3. Lungs
- Symptoms: Often no symptoms at first. Some may experience shortness of breath, chest discomfort, or a long-lasting cough.
4. Liver
- Symptoms: Usually no early symptoms. Some people may feel stomach pain, fatigue, weakness, weight loss, low appetite, or have a fever.
Additional Areas for Lobular Breast Cancer Spread
Lobular breast cancer (a specific type) can spread to other less common areas:
1. Stomach, Small Intestine, or Colon
- Symptoms: Belly pain, bloating, trouble eating, or fluid build-up in the abdomen (ascites).
2. Ovaries or Uterus
- Symptoms: Unusual bleeding or pelvic pain.
3. Bladder and Ureter
- Symptoms: Needing to pee more often, or blood in the urine.
4. Tissues Behind the Eye
- Symptoms: Eye pain or blurry vision.
Why This Matters
Every part of the body may react differently when cancer spreads. Being aware of new changes and staying in touch with your doctor helps catch issues early and leads to better outcomes.
Metastatic Breast Cancer Treatment
This cancer is not curable, but it is treatable. The main goals of treatment are to:
- Slow the growth of cancer
- Shrink tumors when possible
- Relieve symptoms
- Improve the quality of life
- Help patients live longer
Most treatments are systemic therapies, meaning they work throughout the entire body rather than targeting just one area. These treatments are personalized based on factors like the cancer’s hormone receptor status, HER2 status, previous treatments, and overall health of the patient.
Types of Treatment for Metastatic Breast Cancer
1. Hormonal (Endocrine) Therapy
- Used for hormone receptor-positive (HR+) breast cancers.
- These drugs block or lower the body’s estrogen and progesterone, which some breast cancer cells need to grow.
- Often combined with CDK4/6 inhibitors to improve outcomes by slowing cancer cell growth even further.
2. Chemotherapy
- Typically used when the cancer is not hormone-sensitive, is spreading quickly, or has stopped responding to hormonal treatments.
- Works by attacking rapidly dividing cells throughout the body.
- Can help relieve symptoms and shrink tumors, but may also cause side effects like fatigue, nausea, or hair loss.
3. Targeted Therapy
- Targets specific proteins on or in cancer cells—such as HER2 (a protein that helps cancer cells grow).
- Common in HER2-positive metastatic breast cancer.
- Drugs like trastuzumab, pertuzumab, and T-DM1 are examples of targeted therapies.
- These treatments are often more precise, affecting cancer cells while sparing more healthy cells.
4. Immunotherapy
- Helps the body’s immune system recognize and destroy cancer cells.
- Most effective in triple-negative breast cancer (TNBC), especially when combined with chemotherapy.
- Drugs like atezolizumab and pembrolizumab are used in specific cases where the cancer cells express PD-L1 (a protein that helps them hide from the immune system).
Additional Treatments for Symptom Relief
- Radiation therapy may be used to ease pain in specific areas, such as bones or brain.
- Surgery is rare but might be considered to remove tumors causing specific issues or symptoms.
- Bone-strengthening agents may help reduce the risk of fractures if cancer has spread to the bones.
Living with Metastatic Breast Cancer
Treatment is ongoing and often involves managing side effects and adjusting medications as the cancer evolves. Regular monitoring through scans and blood tests helps doctors evaluate how well the treatment is working. Furthermore, individuals can explore potential new treatment options through metastatic breast cancer clinical trials.
Different Types of Breast Cancer
Breast cancer comes in various forms, each with distinct characteristics, progression patterns, and treatment approaches. Understanding the types of breast cancer is essential for choosing the most effective treatment plan and improving outcomes.
Conclusion:
Living with metastatic breast cancer involves ongoing care, treatment adjustments, and emotional strength. Staying informed, proactive, and engaged with your healthcare team can make a significant difference. Exploring new therapies and emerging options can offer hope—especially through participation in clinical trials for breast cancer.
Frequently Asked Questions
What are the first signs of metastatic breast cancer?
The first signs of MBC vary by where it spreads, but common symptoms include bone pain, shortness of breath, fatigue, persistent cough, weight loss, and neurological issues like headaches or vision changes.
Is metastatic breast cancer curable?
No, metastatic breast cancer is not considered curable. Although treatment can help extend life and improve quality of life, the cancer has already spread to other parts of the body and cannot be completely eliminated.
How is metastatic breast cancer diagnosed?
Metastatic breast cancer is diagnosed using imaging tests (CT, MRI, PET, bone scans), biopsies of suspected sites, and blood tests. Imaging locates the spread, biopsies confirm cancer and hormone status, while blood tests offer supportive insights.
How does breast cancer spread?
Breast cancer spreads when cells break away from the primary tumor and travel through the bloodstream or lymphatic system to other organs or lymph nodes.
