Breast cancer spreads to the bones far too often. Bone metastases occur in roughly 70 percent of women with metastatic breast cancer (stage 4 breast cancer) and are often the first sign that cancer has recurred. Thankfully, bone metastases may have a better prognosis than that of breast cancer which has spread to other regions, and several treatments are available which not only reduce pain but may improve survival as well.
Let's take a look at which bones breast cancer most commonly spreads to, the symptoms of bone metastases, the different treatment options available, and possible complications you should be familiar with.
Breast Cancer With Bone Metastases
Breast cancer which spreads to the bone is a source of much confusion, so we will start by defining exactly what this means. Breast cancer which spreads (metastasizes) to bone is still breast cancer. If you took a sample of the tumor in a bone and looked at it under the microscope, you would see cancerous breast cells.
Breast cancer which has spread to the bones is not bone cancer (under a microscope bone cancer would reveal cancerous bone cells). When breast cancer spreads to bones the correct terminology is "breast cancer metastatic to bones." When cancer is found in bones it is much more likely to be metastatic cancer from another area of the body than primary bone cancer.
Addressing bone issues and bone metastases are important no matter what stage of breast cancer a person has. Not only may breast cancer spread to bones, but treatments for breast cancer such as hormonal therapies can lead to bone loss. In fact, medications used for bone metastases bisphosphonates) are now being considered even for those with early-stage breast cancer as a way to strengthen bones and possibly prevent bone metastases from occurring in the first place.
The pain which often accompanies bone metastases, combined with a decrease in mobility due to fractures or a predisposition to fractures, can have a significant impact on quality of life for women living with metastatic breast cancer. Yet, unlike the common perception that there is little you can do if you have stage 4 breast cancer, there is much that can be done to not only reduce the pain and complications of bone metastases but to extend life.
As noted above, bone metastases from breast cancer are the most common site of distant metastases with breast cancer. Bone metastases are slightly more common in women who have estrogen receptor-positive breast cancer (liver and brain metastases are more common in women with HER2 positive and triple negative breast cancer).
Bone metastases are also more common in women with invasive ductal breast cancer than invasive lobular breast cancer (in lobular carcinoma, metastases to the abdomen (peritoneal metastases) are more common). Of the different subtypes of breast cancer, bone metastases are more common in luminal cancers.
Breast cancer has a tendency to spread to some bones in the body more often than others, but this can vary and metastases have occurred to nearly every bone in the body. Metastases occur most commonly to the:
It's not uncommon for bone metastases to occur in a few different bones at the same time, such as the spine and the pelvis. Metastases may also occur in other regions of the body (such as the liver, lungs, or brain) at the same time they are noted in bones.
We don't currently understand why breast cancer spreads to bones. The bones are rich with blood vessels, but so are the liver and lung, areas to which breast cancer spreads but with a lower frequency than bone.
Since metastases are so important (metastases are the cause of death in 90 percent of women who die from breast cancer), this area is being actively investigated.
There is a theory that breast cancer may lie dormant in bone marrow, and the bones which breast cancer most commonly spreads to are those which are rich in bone marrow. If you are interested, you can learn more about the theory of cancer stem cells and dormancy as a possible explanation for why breast cancer can hide for years or decades and then recur.
Bone metastases from breast cancer may be diagnosed in a number of different ways. Sometimes metastases are seen when an x-ray is done for a fracture that occurred with minimal trauma (due to the weakening of a bone due to metastasis, a pathologic fracture). Other times, bone metastases are diagnosed incidentally when a test such as a PET scan is done for another reason. Tests done specifically to look for bone metastases include bone scans and PET scans, with the combination of PET/CT, SPECT/CT, whole body MRI, and PET/MRI offering further sensitivity. There is some debate over the best test, but your oncologist will take several considerations into account when making a recommendation.
A number of different treatments are available for bone metastases. The option which is best for you depends on a number of factors such as the number and location of bones affected, the presence of other metastases, and your general health.
General treatment options for metastatic breast cancer such as chemotherapy, hormonal therapies, and targeted medications are often used, but other options designed specifically to treat the spread of cancer to bones are often used, and can frequently result in the management of cancer for quite some time. These may include:
Pain control - Metastases to bones can be very painful, yet there are many different approaches to relieving pain. Finding the right medications and balancing the side effects of these drugs with adequate pain relief can be challenging. If this becomes difficult, some people work with a palliative care physician or a pain specialist to address the best management for their pain.
Radiation therapy - Radiation therapy is often used and can help both to decrease pain and reduce the risk of fractures. Radiation treatments are "local treatments" which means that it works better for isolated areas of metastases than for widespread metastases.
Radiopharmaceuticals - Radiopharmaceuticals are medications which include a particle of radiation attached to another chemical, which can then be injected into the bloodstream. The radiation is thus delivered directly to the bone metastases. Examples include Strontium-89 and Radium-223. Radiopharmaceuticals may be particularly helpful for those who have multiple or extensive bone metastases which would be difficult to treat with local therapies such as radiation therapy. They have relatively few side effects and can be very effective in controlling bone pain.
Bone-modifying agents - Bone-modifying agents are drugs which can be used orally or by injection to reduce bone metastases. These include:
Surgery - Surgery is used most often to stabilize fractures or areas of bone at risk for fractures (see below).
Possible Complications From Bone Metastases
Bone metastases can lead to many different symptoms and complications. These include:
Difficult-to-manage pain – The pain which accompanies bone metastases can be severe. Pain is often treated with a combination of pain medications and treatments which are designed to reduce the bone metastases. In addition to pain medications, pain specialists have a number of other therapies, including nerve blocks that are sometimes needed.
Fractures/risk of fractures - It's not uncommon for a person to first learn they have bone metastases after suffering a fracture. (Here is an example of a woman with breast cancer and a pathologic hip fracture due to metastases.) Surgery is often done to repair the fractures. With fractures in the long bones of the arms or legs, a rod is usually placed. Not only does this provide support for a weakened bone, but may allow you to become active more rapidly. Vertebroplasty or "cement" may be used for spinal fractures or impending fractures.
Spinal cord compression - Spinal cord compression due to cancer is a medical emergency that can be caused by bone metastases. Infiltration of cancer in the lower spine can lead to the collapse of the vertebrae, and in turn, compression of the nerves that leave the spine to travel to the lower half of the body. Symptoms may include worsening lower back pain which may radiate down the legs, weakness or numbness in one or both legs, and loss of bladder and/or bowel control when breast cancer metastasizes to the spine. Surgical procedures are used to stabilize the spine.
Hypercalcemia – As bones are broken down by cancer, calcium is released into the blood. This, in turn, can lead to constipation, fatigue, extreme thirst, and muscle weakness. When severe, untreated hypercalcemia caused by cancer can lead to kidney failure, coma, and death. First-line treatment includes IV rehydration and bisphosphonates. Sometimes other medications, such as calcitonin, gallium nitrate, or mithramycin may be used. If hypercalcemia is severe, dialysis is another option.
Loss of mobility – The impact of decreased activity associated with recovery from a fracture cannot be stressed enough. With studies telling us that exercise can play a role in survival, even with metastatic breast cancer, anything which reduces your ability to be physically active needs to be addressed carefully.
Poor quality of life - Between the pain related to bone metastases, and immobility related to fractures or risk of fractures, bone metastases can significantly reduce your quality of life. Thankfully, as noted above, there are many options for treatment.
The prognosis of breast cancer which has spread only to bones is somewhat better than for cancers which have spread to other regions of the body. Treatment of bone metastases can sometimes control the disease for a long time. The average overall survival for metastatic breast cancer is 18 to 24 months, with only around 20 percent of people surviving beyond five years. It's important to note again, however, that the prognosis is better for people with only bone metastases and there are some long-term survivors of breast cancer which has spread to bones.
A Word From Verywell
When breast cancer spreads to bones it can be terrifying, especially when this is the way that you discover that your cancer has recurred and you now have metastatic breast cancer.
While bone metastases confirm that your cancer has spread and can be painful, there are some excellent treatment options available, with more treatments currently being evaluated in clinical trials.
Bone metastasis is cancer that started in another part of the body and spread to the bone. It’s sometimes called secondary bone cancer or metastatic bone disease. Bone metastasis is not the same as cancer that starts in the bone (called primary bone cancer). Bone metastases are much more common than primary bone cancer.
Some kinds of cancer are more likely to spread to the bones than others. The most common types of cancer that spread to the bones are:
Cancer can spread to any bone in the body. The most common sites of bone metastases are the vertebrae (bones of the spine), ribs, pelvis (hip bone), sternum (breastbone) and skull. Sometimes only one area of bone is affected. Sometimes metastases develop in several bones at the same time.
Bone is constantly being formed and broken down. This is a normal process that keeps bone healthy and strong. Metastatic cancer can upset this process. It can affect the normal balance between new and old bone and change the structure and function of the bone.
Osteoblastic metastases develop when cancer cells invade the bone and cause too many bone cells to form. The bone becomes very dense, or sclerotic. Osteoblastic metastases often happen when prostate cancer spreads to the bone.
Osteolytic metastases develop when metastatic cancer cells break down too much of the bone, making it very weak. Holes may develop in the bones as the bone is destroyed. Osteolytic metastases often happen when breast cancer spreads to the bone.
Osteolytic metastases are more common than osteoblastic metastases. Osteoblastic metastases and osteolytic metastases can happen together in the same area of bone, such as with metastatic breast cancer.
The symptoms of bone metastases vary depending on which and how many bones are affected. Other health conditions can cause the same symptoms as bone metastases. See your doctor if you have these symptoms.
The most common, and usually first, symptom of bone metastases is pain in the bone. Bone pain can come and go, or it can be constant. It is often worse at night. The pain may be only in one area or it may spread throughout the body. It may be a dull ache or a sharp pain. There may also be swelling along with bone pain.
Other signs and symptoms of bone metastases include:
The following tests may be used to diagnose bone metastases. Many of the same tests can help your healthcare team plan treatment and monitor bone metastases.
Your health history is a record of your symptoms, risk factors and all the medical events and problems you have had in the past. In taking a health history, your doctor will ask questions about a personal history of symptoms that suggest bone metastases.
A physical exam allows your doctor to look for any signs of bone metastases. During a physical exam, your doctor may feel areas that are causing pain or other symptoms, and look for swelling.
Find out more about physical exam.
The types of blood tests used to help diagnose bone metastases include the following.
Complete blood count (CBC) is done to check your general health and how well the bone marrow is working.
Calcium and alkaline phosphatase levels in the blood may be measured. High levels may mean there is damage to the bone from bone metastases.
Tumour markers may be measured if you have had cancer before. They are tests that measure the amount of a specific protein in the body. The type of tumour marker used depends on the type of cancer you had before. For example, prostate-specific antigen (PSA) may be measured in the blood. It is commonly used during follow-up in men who have been treated for prostate cancer. High PSA levels may mean that prostate cancer has come back and spread to the bone.
Imaging tests are an important part of diagnosing bone metastases. It is common for people to have one or more imaging tests when the doctor thinks cancer has spread to the bone. The imaging tests used to diagnose bone metastases include the following.
X-ray is usually one of the first tests used to check symptoms like bone pain. An x-ray can also show breaks, or fractures, of the bones.
Bone scan is used to check the whole skeleton for bone metastases, especially when there is bone pain in several places. A bone scan can often find bone metastases earlier than an x-ray, so it is sometimes used during follow-up after cancer treatment even when there are no symptoms of bone metastases.
Computed tomography (CT) scan is used if x-rays and the bone scan are normal but your doctor still thinks there are bone metastases. It is also used to measure the size of a bone tumour. Doctors may also use a CT scan to guide them to a tumour during a needle biopsy to get tissue samples.
Magnetic resonance imaging (MRI) is used to check for spinal cord compression. It may be used if the results of a CT scan are not clear. MRI can also be used to check if metastatic cancer has spread to the bone marrow.
Positron emission tomography (PET) scan looks at the whole skeleton and may be used to check if there are very small bone metastases. It is rarely used to diagnose bone metastases because other imaging tests are usually needed to follow up on the results of a PET scan.
Find out more about these imaging tests and procedures.
A biopsy is the removal of cells or tissues so they can be examined under a microscope. It is sometimes needed to diagnose bone metastases. If you have a history of cancer, doctors usually base a diagnosis of bone metastases on the results of imaging tests.
Sometimes a biopsy is done if the primary cancer, or where the cancer started, is not known. A needle or surgical biopsy is usually used.
Find out more about biopsy.
If bone metastases are found before the primary cancer is diagnosed, the doctor may order tests to find out where the cancer started. These tests may include:
If you have bone metastases, your healthcare team will create a treatment plan just for you. It will be based on your needs and usually includes a combination of different treatments. Treatments can control and slow the growth of bone metastases, but the metastases usually don’t go away completely. Treatments can also manage or prevent problems caused by bone metastases. These are sometimes called supportive therapies.
When deciding which treatments and supportive therapies to offer for bone metastases, your healthcare team will consider:
You may be offered the following treatments and supportive therapies for bone metastases.
Radiation therapy is a common treatment for bone metastasis. It may be given as external beam radiation therapy or as systemic radiation therapy.
External beam radiation therapy may be used to treat bone pain and spinal cord compression. It is also used to prevent or help heal broken bones, or fractures. During external beam radiation therapy, a machine directs a beam of radiation through the skin. It is directed at a specific area of bone where there is pain or that needs treatment. How long external beam radiation is used depends on the goal of treatment, the number of bones affected by cancer and other factors. A short course of radiation therapy is often used for bone metastases. This usually means that it is given once a day for 5 days. A single radiation treatment may be given.
Systemic radiation therapy may be used when there is pain in many bones. It is most often used for osteoblastic metastases from prostate cancer. Systemic radiation therapy uses drugs with radioactive materials. These drugs are usually given intravenously (through a needle into a vein). They travel through the bloodstream to cancer cells in the bone. The most common radioactive materials used are strontium-89 and samarium-153. Usually only one dose of systemic radiation is given.
Side effects of radiation therapy will depend mainly on the type of radiation therapy, the area of the body treated and the length of treatment. The most common side effect of radiation therapy to the bone is a temporary increase in pain before it gets better or goes away completely.
Bisphosphonates are drugs that help slow the breakdown of bone. They are standard therapy for bone metastases. They are used to help manage and prevent problems such as hypercalcemia, bone pain and broken bones.
When doctors give bisphosphonates depends on factors like where the cancer started, the number of bones affected by cancer, the chance of developing bone problems (such as fractures) and life expectancy. These drugs are usually used along with other therapies such as radiation therapy, chemotherapy and pain medicines.
The most common bisphosphonates used for bone metastases include:
Bisphosphonates are most often given through a needle into a vein (intravenously). These drugs are usually given once every month or once every 3 months, but they may be given more often. Bisphosphonates may also be given once a day as a pill by mouth (orally).
Side effects of bisphosphonates will depend mainly on the type of drug, the dose and the length of treatment. Common side effects of bisphosphonates are flu-like symptoms, diarrhea, nausea and heartburn.
Find out more about bisphosphonates.
A drug called denosumab (Xgeva) may be used instead of bisphosphonates to slow down or stop bone loss caused by bone metastases. Denosumab is a monoclonal antibody that finds and attaches to RANKL, which is a substance on the surface of bone cells. RANKL helps break down bones. When RANKL is targeted and blocked, bones are not broken down as quickly.
Denosumab is given by a needle inserted just under the skin (called subcutaneous injection). It is usually given every 4 weeks or every 12 weeks. While taking denosumab, you may be told to take calcium and vitamin D pills.
The most common side effect of denosumab is low levels of calcium in the blood. Other less common side effects include poor appetite, constipation or diarrhea, fatigue, muscle or joint pain, nausea and vomiting. Tell your healthcare team if you have these side effects or others you think might be from denosumab.
Pain medicines are commonly used to manage pain caused by bone metastases. They are often given because other treatments may take a while to relieve pain or may not stop pain completely.
The most common pain medicines used for bone metastases are taken as a pill, including:
Side effects of pain medicines will depend mainly on the type of drug, the dose and the length of treatment. Common side effects of pain medicines are upset stomach, drowsiness and constipation.
Find out more about pain and how to manage it.
Chemotherapy may be used to help shrink bone metastases and relieve symptoms such as pain. It may be an option if there are several areas of bone metastases, and the cancer is likely to respond to chemotherapy.
Chemotherapy is used to treat many types of metastatic cancer. The type of chemotherapy drug or combination of drugs used depends on where the cancer started.
Chemotherapy uses drugs that circulate throughout the body and destroy cancer cells. The drugs, the dose and the schedule will vary for each person. Chemotherapy is sometimes used along with other treatments such as radiation therapy and bisphosphonates.
Side effects will depend mainly on the type of drug, the dose and how it’s given. Common side effects of many chemotherapy drugs are low blood cell counts (called bone marrow suppression), nausea and vomiting, mouth problems and bowel problems.
Hormonal therapy is a treatment that adds, blocks or removes certain hormones to slow or stop the growth of cancer cells that need hormones to grow. Drugs, surgery or radiation therapy can be used as hormonal therapy.
Hormonal therapy may be offered for some types of cancer that have spread to the bone, such as breast and prostate cancers. It is often used to relieve symptoms like bone pain. It often has fewer side effects than chemotherapy.
Side effects of hormone therapy will depend mainly on the type of hormonal therapy. Common side effects of many types of hormonal therapy are hot flashes and less interest in sex.
Surgery may be used to repair a broken bone caused by metastasis. It may also be used to make bone more stable and prevent it from breaking. Metal screws, pins, rods and plates can be placed during surgery to strengthen and support the bone. Surgery may be used to relieve pain from a broken bone. It can also help prevent or treat spinal cord compression. Most people with bone metastases need to be in good overall health to have surgery.
Side effects of surgery will depend mainly on the site of surgery and your overall health. Common side effects of surgery are pain, bleeding and wound infection.
Bone cement makes bone strong and stable. It may be used to relieve pain from a break, or fracture. It may also be used to prevent a bone from breaking and improve mobility. Bone cement is most often used to treat bones of the spine, pelvis, arms and legs.
Bone cement is a substance called polymethyl methacrylate. It is injected into a bone through the skin. This procedure is also called percutaneous osteoplasty. When it is done on bones of the spine, it is called vertebroplasty. The doctor gives local anesthetic to freeze the area before the needle is inserted. The doctor uses fluoroscopy or CT scan to guide the needle containing the bone cement to the right area of bone.
Possible side effects of injecting bone cement are pain and infection.
Living with bone metastases
In many cases, bone metastasis is a chronic condition. Adjusting to life with bone metastases often takes time. A person with bone metastases may have concerns about the following.
Pain commonly happens with bone metastases. Many treatments and supportive therapies are given to help relieve pain. Tell your healthcare team if treatments are not relieving the pain. You may be referred to doctors and nurses that specialize in ways to manage pain.Having good pain control will help you feel better so you can continue with activities you enjoy.
Some people with bone metastases may want to use complementary therapies, such as acupuncture and massage therapy, to help relieve pain and improve their quality of life. Complementary therapy may help you feel more in control of your health and treatment. Ask your healthcare team to suggest complementary therapies that may help with pain. Find out more about complementary therapies.
Mobility and safety
Bone metastases may lower your mobility, or how well you move around. Bones are often weak and can break easily. You can do the following to lower the risk of falling and keep your environment safe.
Try to move around and change positions slowly. Be careful when you are walking. Wear shoes or slippers with good grips on the bottom. Use a cane or walker to help keep your balance. Ask for help with walking.
Try to keep hallways and walkways clear of clutter. Use safety equipment when bathing, such as shower chairs and handrails.
A diagnosis of advanced cancer can lead to questions about survival. There is no way of knowing exactly how long someone will live with bone metastases. It depends on many factors, including the type of cancer. For example, survival with bone metastases from prostate or breast cancer is often measured in years. Survival with lung cancer that has spread to the bones is often measured in months. Some people live much longer than expected, while others may die sooner than expected.
The best person to talk to about survival is the doctor. The doctor may be able to estimate survival based on what they know about a person and the type of cancer, but it’s not an exact science.