Where breast cancer can spread

When Cancer Goes Beyond Your Breast

If your doctor told you that your breast cancer has spread to other parts of your body, it's at a more advanced stage than if it's only in your breast or breasts. How far it's spread is one of the things your doctor will consider when she tells you the "stage" of your cancer. It's considered "metastatic" if it has spread far from your breasts. Every case is different. For some women, it becomes something they live with for a long time. For others, focusing on pain management and quality of life is the main goal.
Most Common Places It Spreads

It's still breast cancer, even if it's in another organ. For example, if breast cancer spreads to your lungs, that doesn't mean you have lung cancer. Although it can spread to any part of your body, there are certain places it's most likely to go to, including the lymph nodes, bones, liver, lungs, or brain.
Lymph Nodes

The lymph nodes under your arm, inside your breast, and near your collarbone are among the first places breast cancer spreads. If it spreads beyond these small glands to other parts of the body, it’s considered "metastatic." When you're diagnosed with breast cancer, your doctor should check lymph nodes near the tumor to see if they're affected. The lymph system helps drain bacteria and other harmful substances from your body. You might not notice symptoms if your breast cancer is in your these nodes.
Bones

When breast cancer is in your bones, pain is usually the first symptom. It can affect any bone, including the spine, arms, and legs. Sometimes the bone may be weak enough to break, but treatment often prevents that. You might also have numbness or weakness in a part of your body, like an arm or leg. If the cancer involves your spinal cord, it can also cause problems with incontinence or going to the bathroom.
Liver

If breast cancer spreads to your liver, you may have pain in your abdomen that doesn’t go away, or you might feel bloated or full. You might also lose your appetite and lose weight. You may notice that your skin and the whites of your eyes are turning yellow, which is called jaundice.
That happens because your liver isn’t working right.
Lungs

Breast cancer can spread to the lungs or to the space between the lung and the chest wall, making fluid build up around the lung. Symptoms can include shortness of breath, a cough that won’t go away, and chest pain. Some people lose their appetite, leading to weight loss.
Brain

It's possible for breast cancer to spread to the brain. That can cause headaches that throw off your balance and make falls more likely. You may have numbness or weakness in one part of your body. You might act differently, or you could feel confused or have seizures.
Treatments

You may need surgery, chemotherapy, radiation, and medications. The drugs your doctor recommends will depend on your type of breast cancer. For instance, if the hormone estrogen spurs your cancer cells to grow, your doctor would choose different treatment from someone who has HER2 breast cancer, in which a certain protein drives the growth. Pain management is also key, so you feel as well as possible.

(From webMD)