Complications of Advanced (Metastatic) Breast Cancer

Potential Problems Resulting From Stage 4 Breast Cancer

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Advanced (stage 4) breast cancer involves metastases, which is the spread of cancer to other parts of the body. The effects vary, depending on the areas of the body that cancer has spread to, and may include problems such as blood clots, muscle wasting, shortness of breath, seizures, and more.

Most of the complications of advanced breast cancer are treatable, and treatments are most effective when they are started sooner rather than later. In some cases, recognizing a complication early can prevent serious problems, such as paralysis or even death.

stage 4 metastatic breast cancer complications

Verywell / Brianna Gilmartin

General Complications

Metastatic breast cancer can cause certain complications regardless of the location of the metastases.

Blood Clots

Metastatic cancer, some cancer treatments (such as chemotherapy), and bed rest can all increase the risk of blood clots. Blood clots with cancer are among the most common complications. They cause considerable illness and can be fatal.

Blood clots often begin in the legs or pelvis (deep vein thrombosis) and can break off and travel to the lungs (pulmonary embolism).

Symptoms to look out for include:

  • Redness, swelling, or tenderness of your leg or arm
  • Sudden shortness of breath
  • Sudden severe chest pain
  • Lightheadedness
  • Unconsciousness

Blood thinners are often used to resolve the clots, and sometimes a procedure may be necessary to remove the blood clot.


Pain with metastatic cancer can be variable and often depends on the location of metastases. Pain can interfere with your quality of life, and maintaining your quality of life is a primary goal in treating stage 4 cancer.

Talk to your healthcare provider about pain control. Many options are available, and most people, even with severe end-stage disease, can be comfortable.


Cancer cachexia is a challenging issue with advanced cancer. It's a syndrome of involuntary weight loss, muscle wasting, and reduced appetite. It reduces quality of life and is felt to be the direct cause of death for 20% of people with cancer. If you're struggling with loss of appetite or if you have lost weight, be sure to discuss it with your healthcare provider.

While it sounds counterintuitive, exercise can sometimes be helpful.

Complications Related to Bone Metastases

The bones are the most common site to which breast cancer spreads. Multiple complications may result from bone metastases.

For those who have breast cancer with bone metastasesbone-modifying drugs such as bisphosphonates and denosumab may reduce the risk of complications such as fractures.


The pain due to bone metastases can be excruciating, and it can severely diminish your quality of life. Furthermore, many of the medications that are used to treat severe pain can cause fatigue and drowsiness.

Radiation therapy is often effective for reducing pain due to bone metastases. Bone-modifying drugs don't reduce pain to the same degree, but they can be helpful when used along with other treatments.

Pathological Fractures

A pathological fracture occurs when a weakened bone breaks. Depending on the location, a fracture of this sort can substantially decrease mobility. You will need time to fully heal if you've had a fracture.

Spinal Cord Compression

Spinal cord compression due to cancer is a medical emergency. When bone metastases occur in the lower spine, they can cause the spine to compress—which can impair functions such as walking, urinating, and having bowel movements.

A very serious form of microfracture in the spine can lead to vertebrae in the back collapsing down on themselves, which is called a compression fracture. When cancer in the low region of the region causes spinal cord or nerve compression, a medical emergency known as cauda equina syndrome may occur.

Without prompt treatment to stabilize the spine after a fracture, a person may end up paralyzed in the lower extremities and unable to control their bladder or bowels.


When a tumor breaks down bone, calcium is released into the bloodstream, a condition called hypercalcemia of malignancy.

Early on, this may cause:

  • Nausea and vomiting
  • Increased thirst
  • Weakness
  • Muscle aches

It can progress to serious symptoms, including:

  • Confusion
  • Abnormal heart rhythms
  • Coma
  • Death

Complications Related to Lung Metastases

The lungs are the second most common site to which breast cancer spreads, with lung metastases occurring in roughly a third of people with metastatic breast cancer.

Sometimes this doesn't cause symptoms, and the lung metastases might only be found on an imaging test. The most common symptom is shortness of breath.

Local treatments, such as radiation or surgery, are sometimes used for the treatment of one or more lung metastases, and this may improve life expectancy.

Shortness of Breath

Shortness of breath can often be controlled with medications such as morphine. If it's caused by an obstruction, a stent may be placed to open the airway.

Generally, oxygen supplementation is not helpful in reducing the sensation of shortness of breath because the airways may be blocked—preventing oxygen from getting into the lungs.


The presence of metastases in the lungs, especially near the airways, can lead to the accumulation of fluid and bacteria deep in the lungs. This can lead to recurrent pneumonia.

Pneumonia can be more serious if your white blood cell count is reduced due to chemotherapy, and this infection often requires hospitalization and intravenous antibiotics.

Malignant Pleural Effusion

malignant pleural effusion is a condition in which fluid and cancer cells build up between the pleura (membranes) that line the lung. The severity varies depending on the amount of fluid and how rapidly it accumulates.

A small pleural effusion may not need to be treated. A large pleural effusion, though, can compress the lungs, leading to severe pain and shortness of breath.

The first step in treatment is usually a thoracentesis, in which a needle is inserted through the chest wall into the pleural space to drain the fluid. Unfortunately, the fluid often recurs.

Further treatment options include:

  • Repeated draining
  • Having a catheter inserted so your effusions can be drained at home
  • Pleurodesis, a procedure in which a chemical that causes inflammation is inserted into the pleural space, which results in "gluing" of the membranes together so that fluid may not re-accumulate

Pulmonary Hemorrhage

Pulmonary hemorrhage, or bleeding into the lungs, isn't common, but it may occur. This is a medical emergency that may be fatal unless it's treated promptly.

Coughing up blood may occur, especially when metastases are near the large airways. Even a small amount of blood—like a teaspoon—is considered a medical emergency. Coughing up a third of a cup of blood has a mortality rate of around 30%.

Be sure to get immediate medical attention for symptoms that may be related to pulmonary hemorrhage, which include:

  • Difficult or labored breathing
  • Cough
  • Fever
  • Acute respiratory failure

Don't ever ignore it if you cough up blood, even if it doesn't seem like much. When this problem is diagnosed promptly, a procedure can often stop the bleeding.

Obstruction of the Airways

When metastases grow near or into the airways, they may cause an obstruction.

This can lead to:

  • Shortness of breath
  • Infections such as pneumonia

If an obstruction is severe, healthcare providers can place a stent in the airway to hold it open.

Complications Related to Liver Metastases

Liver metastases may not cause any symptoms unless the metastases are near the major vessels and ducts of the liver.

If you have symptoms, you may notice:

  • Jaundice (yellowing of the skin and whites of the eyes )
  • Abdominal pain
  • Shoulder pain
  • Hiccups


With extensive metastases, confusion and lethargy may occur due to the build-up of toxins in the body. This is a medical emergency that requires immediate attention.


The liver is responsible for making clotting factors for the blood. If this organ is largely non-functioning, the result can be an insufficient amount of clotting factors, which can lead to bleeding and anemia. Treatment with supplemental clotting factors or a blood transfusion may be necessary.


You may not think of itching as a serious complication, but the itching that can accompany liver metastases can be severe.

It occurs due to the build-up of bile acids in the blood and skin. Ask your healthcare provider about medications to reduce this symptom.

Complications Related to Brain Metastases

Brain metastases are also common in breast cancer and may result in any number of symptoms, some which can be life-threatening.

You may experience a complication of brain metastases before knowing that cancer has spread to your brain.


Seizures can cause a variety of symptoms based on the type, ranging from muscle stiffness to brief episodes of diminished awareness.


Brain metastases can lead to:

  • Weakness
  • Numbness
  • Loss of balance

Any of those symptoms can contribute to the risk of falls, which can result in serious injury and disability. If brain metastases are present, it's important to be extra careful about fall prevention.

Other complications of brain metastases may include:

  • Visual problems, such as double vision or loss of vision
  • Sudden changes in mental status or personality
  • Loss of consciousness

The treatment for brain metastases is often radiation. If only one or a few metastases are present, a specialized form of radiation therapy called stereotactic body radiotherapy (SBRT) may be used in an attempt to eradicate the metastasis.

Complications Due to Other Metastases

Breast cancer can spread to nearly any region of the body. If you have symptoms, even if they're seemingly unrelated to your cancer, make sure to talk to your oncologist.

Pericardial Effusion

Breast cancer can spread to the lining of the heart and cause pericardial effusion.

When fluid builds up between the membranes lining the heart, your heart has to work harder. The heart rate usually speeds up to make up for the smaller volume it's pumping out.

If the fluid builds up quickly or is extensive, it can lead to a condition known as pericardial tamponade, basically restricting the heart so much that it is unable to beat. When this condition occurs due to cancer metastases, a third of people die before it can be diagnosed and treated. Fortunately, this complication isn't common.

Be certain you talk to your healthcare provider if you experience any increased shortness of breath or a rapid heart rate.


With spread of cancer to the peritoneal cavity, fluid can build up in the peritoneal cavity, causing ascites. If your abdomen becomes very distended, it can be painful and cause shortness of breath (especially if you also have lung metastases).

Healthcare providers may do a procedure called a paracentesis in which a needle is inserted through the skin and into the abdominal cavity to drain off the fluid.

Brachial Plexus Injury

When cancer spreads into the tissues under the arm, it may damage a group of nerve fibers known as the brachial plexus. This can cause weakness or paralysis in the arm on that side.

Brachial plexopathy due to breast cancer affects only 1 in 200 women, and it is a very disabling complication.

Complications Due to Treatment

Other serious complications that may occur are similar to those that can happen to people with early-stage breast cancer. These can happen during and after treatment.

Heart Disease

Both chemotherapy and radiation therapy can damage the heart. Heart disease may appear many years after the initial treatment and can include coronary artery disease, heart failure, and/or valve problems.

The most common of these is heart failure, which often causes shortness of breath, swollen extremities, and coughing up pink, frothy sputum.


If you are on chemotherapy, your healthcare provider has likely warned you about developing a neutropenic fever, which can be a life-threatening complication for you.

When your immune system is suppressed, your ability to fight off infections is weakened. Even mild infections may require hospitalization and intravenous antibiotics.

If you think that you may have an infection, don't wait. Call your oncologist.

Allergic Reactions

When you're living with stage 4 breast cancer, you may be using several medications, including cancer therapies and symptomatic treatments. Even if you've taken a medication before without problems, the next dose could result in a severe allergic reaction.

Ideally, everyone should be aware of the symptoms of anaphylaxis, a severe allergic reaction, as this can be life-threatening. If you notice any swelling of your neck, tongue, or face, hives, or lightheadedness, seek medical attention.

Psychological Complications

You may not think of depression as a complication of metastatic cancer, but it is a very important aspect of your illness and your quality of life. This battle is a tough one that can affect the mental health of any person, whether they come across as a "fighter" or not.

The goal of treatment is to extend your years while giving you the best quality of life possible. If your mood is interfering with your ability to enjoy your family and friends, you should discuss this with your oncologist, a palliative care specialist, or a therapist.

A Word From Verywell

There are many different potential complications that may develop due to metastatic breast cancer. It's also important for you to know that many people do not experience complications at all. As you are managing your disease, be aware of your body and talk to your oncologist about any concerns that you have. Even serious complications can be treated, especially when they are identified early.

19 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Maltser S, Cristian A, Silver JK, Morris GS, Stout NL. A Focused Review of Safety Considerations in Cancer Rehabilitation. PM R. 2017;9(9S2):S415-S428. doi:10.1016/j.pmrj.2017.08.403

  2. Abdol Razak NB, Jones G, Bhandari M, Berndt MC, Metharom P. Cancer-Associated Thrombosis: An Overview of Mechanisms, Risk Factors, and Treatment. Cancers (Basel). 2018;10(10). doi:10.3390/cancers10100380

  3. American Heart Association. Symptoms and Diagnosis of Venous Thromboembolism (VTE).

  4. Aoyagi T, Terracina KP, Raza A, Matsubara H, Takabe K. Cancer cachexia, mechanism and treatment. World J Gastrointest Oncol. 2015;7(4):17-29. doi:10.4251/wjgo.v7.i4.17

  5. Steger GG, Bartsch R. Denosumab for the treatment of bone metastases in breast cancer: evidence and opinion. Ther Adv Med Oncol. 2011;3(5):233-43. doi:10.1177/1758834011412656

  6. Kang J, Formenti SC. Metastatic Osseous Pain Control: Radiation Therapy. Semin Intervent Radiol. 2017;34(4):322-327. doi:10.1055/s-0037-1608703

  7. Willeumier JJ, Van der linden YM, Van de sande MAJ, Dijkstra PDS. Treatment of pathological fractures of the long bones. EFORT Open Rev. 2016;1(5):136-145. doi:10.1302/2058-5241.1.000008

  8. Delank KS, Wendtner C, Eich HT, Eysel P. The treatment of spinal metastases. Dtsch Arztebl Int. 2011;108(5):71-9. doi:10.3238/arztebl.2011.0071

  9. American Society of Clinical Oncology (ASCO). High Calcium Levels or Hypercalcemia.

  10. Desai NR, Lee HJ. Diagnosis and management of malignant pleural effusions: state of the art in 2017. J Thorac Dis. 2017;9(Suppl 10):S1111-S1122. doi:10.21037/jtd.2017.07.79

  11. Farbicka P, Nowicki A. Palliative care in patients with lung cancerContemp Oncol (Pozn). 2013;17(3):238–245. doi:10.5114/wo.2013.35033

  12. Larson VA, Tang O, Ständer S, Kang S, Kwatra SG. Association between itch and cancer in 16,925 patients with pruritus: Experience at a tertiary care center. J Am Acad Dermatol. 2019;80(4):931-937. doi:10.1016/j.jaad.2018.08.044

  13. Martin AM, Cagney DN, Catalano PJ, et al. Brain Metastases in Newly Diagnosed Breast Cancer: A Population-Based Study. JAMA Oncol. 2017;3(8):1069-1077. doi:10.1001/jamaoncol.2017.0001

  14. National institute of Neurological Disorder and Stroke. Brain and Spinal Cord Tumors: Hope Through Research.

  15. Stukan M. Drainage of malignant ascites: patient selection and perspectivesCancer Manag Res. 2017;9:115–130. Published 2017 Apr 12. doi:10.2147/CMAR.S100210

  16. Gandhi SJ, Rabadiya B. Metastatic Brachial Plexopathy with Brain and Spinal Metastasis in a Case of Recurrent Breast Carcinoma Demonstrated on F-FDG PET/CT. Indian J Nucl Med. 2017;32(2):118-121. doi:10.4103/0972-3919.202252

  17. Aleman BM, Moser EC, Nuver J, et al. Cardiovascular disease after cancer therapy. EJC Suppl. 2014;12(1):18-28. doi:10.1016/j.ejcsup.2014.03.002

  18. Do Nascimento TG, De Andrade M, De Oliveira RA, De Almeida AM, Gozzo Tde O. Neutropenia: occurrence and management in women with breast cancer receiving chemotherapy. Rev Lat Am Enfermagem. 2014;22(2):301-8. doi:10.1590/0104-1169.3305.2416

  19. Castells M. Drug Hypersensitivity and Anaphylaxis in Cancer and Chronic Inflammatory Diseases: The Role of Desensitizations. Front Immunol. 2017;8:1472. doi:10.3389/fimmu.2017.01472

By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."