Stage 4 breast cancer means that cancer cells that first show up in the breast have metastasized, or spread, to other areas of the body. Common areas for metastases include the lymph nodes, bones, lungs, liver, and brain. Other terms for stage 4 breast cancer include advanced or metastatic breast cancer.

By definition, stage 4 breast cancer involves complications, as it has already moved beyond the original cancer site. But additional complications can occur from the cancer itself or due to treatments. These complications may vary depending on the type of cancer, where it has spread, and what treatment methods are in use.

Here are some potential complications you may face with advanced breast cancer, and how to manage them.

Cancer can cause pain all on its own, as tumors grow and take over formerly healthy areas of the body. The cancer can put pressure on organs, nerves, and bones, causing aching or sharp, stabbing pain. Some types of cancer even secrete certain chemicals that can cause painful sensations.

Your healthcare team can help determine the best course of treatment for managing pain. This may include over-the-counter pain relief options, prescriptions, or a complementary therapy.

Breast cancer commonly spreads to the bones, which can lead to a few complications. These complications are often caused by bone resorption, a normal process of breaking down bone. In healthy young people, bone is rebuilt at the same rate as it is broken down. In older adults and those with metastasis to the bones, the resorption process occurs more rapidly.

Bone pain

A painful, aching feeling in your bones is often the first sign that cancer has spread to the bone. As the condition progresses, resorption causes a thinning and weakening of the bones. When the bones become too weak, fractures can occur, sometimes without any major injury causing the damage.

Spinal compression

When cancer cells grow in or near the spine, they can put pressure on the spinal cord and adjacent nerves. This pressure can cause pain in the back or neck, numbness or tingling, and difficulty walking. Sometimes, it can lead to difficulty controlling the bladder and bowels. Spinal compression is less common than other bone complications, but it can be very serious.


Hypercalcemia refers to elevated levels of calcium in the blood. This occurs when the rate of resorption increases, and calcium from the bones is released into the bloodstream. Hypercalcemia can lead to serious problems, such as:

  • kidney stones
  • kidney failure
  • irregular heartbeat
  • neurological problems, including confusion, dementia, or coma

Treating bone complications

A certain class of drugs, called bisphosphonates, works to slow the rate of resorption. These drugs work by destroying osteoclasts, the cells responsible for resorption. This helps to lower blood calcium levels, slow the weakening of bone structure, and lessen bone pain.

Breast cancer that spreads to the lungs doesn’t always lead to symptoms and complications. But if you do experience symptoms, you may have shortness of breath, wheezing, chest pain or discomfort, or a cough that doesn’t go away.

If your healthcare team discovers breast cancer cells in a lung tumor, the best way to treat this is to continue systemic medications like chemotherapy or targeted therapy.

Breast cancer cells can sometimes lead to a complication called a pleural effusion. This is when cancer cells end up in the fluid that surrounds your lungs. This requires a procedure to remove the excess fluid.

Roughly half of people with a metastatic breast cancer diagnosis may have cancer cells travel to their liver. Tumors that form can affect the function of your liver.

You may not experience symptoms, but early signs include pain or fullness in your stomach. More serious symptoms include sudden weight loss, vomiting, or jaundice. Jaundice is a condition that causes yellowing of the skin or the whites of the eyes.

Sometimes, the cancer may cause a blockage in your bile ducts, which help your liver remove waste. If this occurs, you’ll need to undergo a procedure to unblock your bile ducts.

Another area that breast cancer cells can spread to is the brain. While this may sound alarming, there are treatments available that can remove or shrink these tumors.

Brain metastases may affect your vision, memory, and behavior. Symptoms can include frequent headaches, dizziness, nausea, vomiting, and seizures. If you develop seizures or swelling in the brain, your doctor may prescribe a corticosteroid or anti-seizure medication.

Your healthcare team can determine if cancer has spread to your brain through imaging tests like CT scans and MRIs. If these tests can’t confirm a diagnosis, you may need a surgeon to perform a biopsy.

Treatments include a craniotomy, which is a type of surgery, and radiation therapy. Sometimes, tumors can form around your brain and spinal cord. If this happens, you may need a specific type of chemotherapy called intrathecal chemotherapy.

Cancer treatments involve getting rid of abnormal and normal cells from the body, so you may experience unpleasant side effects. In some cases, you may feel like the treatment is even worse than the cancer. It’s important to realize that the pain and discomfort of treatment will go away. Healthy cells do recover.

Cancer treatments can cause pain and sickness. Chemotherapy treatments may result in mouth sores, nausea, nerve damage, and diarrhea. Radiation therapy can lead to burning pain and scarring. Surgery can be painful and may require significant time for recovery.

When doctors remove lymph nodes to check for cancer cells, this disrupts the flow of lymph fluid in the body. If not enough lymph nodes are left to properly drain fluid from a particular area, a form of painful swelling called lymphedema can occur.

Lymphedema is best caught early. It can be treated with physical therapy, massage, or a compression sleeve. Pain can be treated with over-the-counter pain relievers, or a doctor may prescribe a stronger painkiller. Side effects from chemotherapy can sometimes be treated with other medications.

Any time you experience pain or other unpleasant complications from your cancer or your treatment, let your doctor know. They can determine if the symptoms indicate a more serious problem, and can also work with you to manage symptoms and help you feel better, faster.