Metastatic breast cancer – also called advanced or stage IV breast cancer – is cancer that spreads to other parts of the body. Even when the breast cancer spreads to other organs of the body, it is still called and treated as breast cancer. Metastatic cancer can arise several months and even years after you have successfully treated early or locally advanced breast cancer. This often makes cancer patients wonder where breast cancer spreads to. Let's find out more about it.

Where Does Breast Cancer Spread To?

When you receive treatment for breast cancer and even recover, it is possible for cancer to grow back again and this time the cells can affect other organs. Here is more about the organs your breast cancer can affect.

1. Bones

About 25% of all breast cancer patients end up dealing with cancer of the bone as well. The most affected bones include the bones of the spine, pelvis, ribs, skull, and long bones of the legs and arms. You can have one of two types of metastases – osteolytic and osteoblastic. In case of osteolytic metastases, the cancer damages your bones and leaves holes in them. This most often affects your bones in the hip, legs, and pelvis. On the other hand, osteoblastic metastases increase your bone mineral density, which makes your bones fragile and they fracture easily. You experience severe pain with both types of metastases, but there can be other complications, including the surgical treatment for fractures, spinal cord compression, and hypercalcemia.

2. Lungs

About 70% of women who die from breast cancer also have it spread to their lungs. The lung can be the only site of spread – it happens in about 21% of cases. The problem is that you do not experience any new symptoms after the cancer spreads to the lungs. Only CT scan and X-ray help detect the problem. Sometimes, it is important to remove the part of the lung through a surgical procedure to limit the cancer to one area only. You usually require chemotherapy and other anti-cancer drugs to deal with breast cancer that as spread to your lung.

3. Liver

After lung and bone, the liver is the most common site for breast cancer to spread to and it affects about two-thirds of all women who have breast cancer. You may experience symptoms of liver metastases but they can be so subtle to be noticed at first. The most common include loss of appetite, weight loss, gastrointestinal disorders, and fever. You may have to take liver blood tests to confirm the diagnosis – a liver biopsy may also be necessary in some cases.

4. Lymph Nodes

Where does breast cancer spread to? Lymph nodes. Cancer cells can actually travel to different parts of your body through lymph nodes, which are under the arm, near the collarbone, and along the center of your ribcage.

5. Muscle, Fatty Tissue and Skin

You may develop cancer in the muscle or skin near the area where the initial tumor was. It means that you can develop cancer on the surgical scar you get after the treatment of your breast cancer. It is somewhat easier to detect and treat the cancer that spreads to these specific areas, but these metastatic sites usually indicate the start of a widespread metastatic disease.

6. Bone Marrow

When you have metastatic breast cancer, you already have cancer cells in your bone marrow, especially when you have bone metastases. The cancer of the bone marrow usually goes undetected until it has already become quite serious. It leads to a considerable decrease in the number of red or white blood cells – that is when most doctors order a bone marrow biopsy to confirm the diagnosis.

7. Brain

Any kind of metastatic cancer is capable of affecting your brain, but certain types are more likely to cause serious damage, such as the HER2-positive and triple negative. These types are diagnosed after considering the symptoms, which usually depends on the pressure exerted by the tumor. Some of the most common symptoms include seizure, headache, dizziness, and visual disturbances.

How Does Breast Cancer Spread?

Knowing the answer to, "where does breast cancer spread to?" is important but it is equally important to know how it actually spreads. New tumors can develop when these cells affect another organ in the body. Cancer cells are not like normal cells – they cannot stick together like normal cells. They can break away from the original site and travel to other areas of the body. Cancer cells can travel from one organ to another through the bloodstream or lymphatic system.

• Cancer cells can spread through the bloodstream once they enter the small blood vessels. Known as circulating tumor cells, these cells continue to travel throughout the body until they get stuck somewhere.
• These cells can also spread through the lymphatic system, which is a network of glands and tubes in the body, designed to fight infection and filter body fluid. These cells can go into the small lymph vessels close to the tumor in the breast and then can travel through lymph vessels to lymph glands. Some of these cells are destroyed by the lymph nodes but some can survive and cause all sorts of complications.