When breast cancer spreads to other parts of the body, it’s called metastatic breast cancer. Knowing the common places where breast cancer spreads can help you and your healthcare team monitor your health and catch problems early.
Not all breast cancer is the same, and the type of breast cancer can influence where breast cancer may spread. The types of breast cancer are determined by the receptors found on the outside of the cancer cells. These types include:
Lymph Nodes
Lymph nodes are small, bean-shaped glands in your immune and lymphatic systems. Connected through small lymphatic vessels, lymph nodes filter fluid. Clusters of lymph nodes are located under the armpit near the breast, and the lymph nodes are often the first place breast cancer spreads. Other lymph nodes typically affected are near the collarbone or in the chest.
Bones
About 70% of people with metastatic breast cancer experience metastases to the bones. Cancer cells can travel through the bloodstream or lymphatic system and deposit in the bone, where they interfere with the normal bone remodeling process.
This usually causes the affected bones to become weak and increases the risk of fracture. Bone metastases can occur in any part of the skeleton, but the spine, hips, and ribs are common sites.
Lungs
The lungs are another common site for breast cancer metastasis, mostly due to the large network of blood vessels that provide an easy pathway for cancer cells to deposit. When breast cancer cells spread to the lungs, no noticeable symptoms may be present at first.
Liver
The liver is a common site for metastatic breast cancer due to its role as a major filter for blood. Cancer cells circulating in the bloodstream can deposit themselves in the liver, where they grow and form tumors. Since the liver is critical in filtering toxins from the blood, metastasis here can cause serious health complications.
Brain
Though brain metastases are not as common as bone or liver metastases, breast cancer can spread to the brain, with the HER2-positive and triple-negative subtypes at the highest risk.
Cancer cells can enter the brain by crossing the blood-brain barrier, a protective mechanism designed to keep harmful substances out of the brain. Once in the brain, cancer cells can cause tumors to grow or grow in the fluid surrounding the brain and the spinal cord.
Peritoneal Cavity
The peritoneal cavity, which contains the abdominal organs, is a less common but still potential site for breast cancer to spread. This area contains the peritoneum, a thin layer of tissue that lines the abdominal wall and covers the organs. Breast cancer cells can spread to this region and diffuse (spread) through the cavity’s lining.
How Breast Cancer Spreads
The metastatic process of breast cancer is complex. It begins when breast cancer cells break away from the original tumor in the breast. These cells travel through the bloodstream or the lymphatic system to other parts of the body.
As they travel through the body, some cancer cells are too big to fit through the microscopic blood vessels and may start to grow there. In other instances, other processes allow the cancer cells to continue through without difficulty and continue to spread. They can grow and form new tumors once they settle in a new area.
This process is called metastasis. Not all cancer cells will spread, but some may find the right conditions to grow in other tissues. Research is ongoing to determine exactly how breast cancer spreads and ways to help treat it more effectively.
Signs Your Breast Cancer Has Spread
Metastatic breast cancer can cause different symptoms depending on where it spreads. Here are some general signs to watch for:
- Changes in vision or balance
- Fatigue that doesn’t go away
- Persistent pain in one area
- Shortness of breath or persistent cough
- Swelling or lumps in unusual places
- Unexplained weight loss
Less Common Sites of Distant Metastases
Breast cancer can spread to other parts of the body, though these are much less common:
- Adrenal glands
- Eyes
- Heart
- Kidneys
- Pancreas
- Skin
What to Do If Your Breast Cancer Has Spread
If you are worried that your breast cancer has spread, it’s important to talk to your healthcare team as soon as possible. They can run tests, such as scans or blood work, to find out if the cancer has spread and to what sites.
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