Like any cancer, breast cancer can spread to other parts of the body. Breast cancer that has invaded bone can have a significant effect on quality of life, but there are treatments to help manage symptoms and slow disease progression.
Read on to learn more about metastatic breast cancer in bones, including symptoms and what you can expect of treatment.
“Metastasis” describes the spread of cancer from where it started to another part of the body. This happens when cancer cells break from the primary tumor and enter the lymph system or bloodstream. From there, they can travel throughout the body and form new tumors.
Metastatic breast cancer in bones is not the same as bone cancer. It’s made up of breast cells, not bone cells. It’s also called stage 4 or advanced breast cancer.
A 2019 research review showed that bone is the most common site of breast cancer metastasis. Breastcancer.org says that for more than half of women with metastatic breast cancer, bones are the first site of metastasis. The bones most likely to be affected are:
- long bones in your arms and legs
Other common sites of breast cancer metastasis include your liver and lungs.
Signs and symptoms vary depending on where the cancer has spread and how big the tumors are.
Bone pain from breast cancer metastasis tends to be constant. It may get worse when you’re active and typically doesn’t let up when you rest. This can make it difficult to sleep well.
Cancer weakens bone, making it fragile and susceptible to fracture. Sudden, severe bone pain can be due to a fracture, even after a minor injury.
Compressed spinal cord
Cancer in your spine puts pressure on nerves. This can lead to back or neck pain. It can also cause numbness or weakness in your legs, as well as bladder and bowel concerns.
Cancer can cause bone to break down and leak calcium. Hypercalcemia is a condition in which you have a high level of calcium in your blood. Symptoms can include:
- frequent urination
- thirst, dehydration
- nausea, loss of appetite
Your doctor will likely start with a discussion of your symptoms and a physical examination.
Diagnostic testing may include blood tests to find out if your blood has too much calcium or alkaline phosphatase (ALP), either of which can be elevated because of bone metastasis. But this can also be due to other conditions. Blood tests alone can’t confirm metastatic breast cancer in bones or pinpoint the location.
Sometimes, an X-ray can reveal bone metastasis. But other times, your doctor may order one or more of the following imaging tests to look for signs that cancer has reached bone:
- Bone scan. A bone scan is a type of nuclear medicine test. Before the scan, a small amount of a radioactive substance is injected into a vein. This causes cancer to show up as dark areas or “hot spots” on the scans.
- Computerized tomography (CT) scan. A CT scan combines X-ray and computer technology to provide cross-sectional images. It can highlight the inside of a specific bone or area of bone.
- Magnetic resonance imaging (MRI) scan. MRI uses radio waves and a magnetic field instead of X-rays to create detailed images of specific bones.
- Positron emission tomography (PET) scan. A PET scan is a nuclear imaging test. Radioactive tracers allow cancer cells to appear as bright spots on the scans.
- Bone biopsy. In some cases, your doctor may want to do a bone biopsy to confirm the diagnosis and get more information about the cancer. Metastatic cancer in your bones may have different characteristics from the primary breast cancer. This information can help determine which treatments are most likely to be effective.
Breast cancer isn’t a single disease, but a group of diseases. So, treatment is personalized to reflect your:
- specific type of breast cancer
- extent of metastasis
- previous treatments
- age and overall health
Depending on your level of pain, medications may include acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs). Your doctor may also prescribe narcotics for relief of severe pain. You might also give acupuncture a try.
Local treatment depends on which bones are affected and how weak they’ve become. Treatment may include:
- Radiation therapy. This therapy destroys cancer cells in your affected bone.
- Surgery. This treatment may help stabilize a fractured bone.
- Bone-strengthening drugs. These medications include bisphosphonates and denosumab to strengthen bones and reduce related skeletal injuries such as fractures, spinal cord compression, or other complications from bone metastases.
Your options for systemic treatment vary according to the characteristics of the cancer. This includes hormone and HER2 receptor status, as well as other specific tumor markers or genetic mutations. Any previous cancer treatments should also be considered and adjusted if necessary.
Systemic treatments may include:
- chemotherapy such as topoisomerase inhibitors, mitotic inhibitors, anti-metabolites, anti-tumor antibiotics, and corticosteroids
- hormone therapy such as tamoxifen, aromatase inhibitors or fulvestrant
- anti-HER2 drugs such as trastuzumab, pertuzumab, and many others
- targeted therapy such as CDK4/6 inhibitors, PARP inhibitors and many others
- immunotherapy (biologic therapy) such as atezolizumab or pembrolizumab in combination with chemotherapy
Clinical trials are studies that research the effectiveness of new therapies. By participating in a trial, you may have access to innovative treatments that aren’t available anywhere else. If you’re interested, ask your doctor for information about trials that might be a good match.
Treatment for bone metastasis can effectively manage metastatic breast cancer for some time. Many people with bone metastasis continue to have a good quality of life and live for many years. That said, treatment for metastatic cancer doesn’t usually eliminate all cancer cells, and eventually, these cells become resistant to therapy.
According to the American Cancer Society (ACS), the 5-year survival rate for metastatic breast cancer is 28 percent for women and 22 percent for men. It’s important to note that cancer survival statistics are based on people who were diagnosed and treated at least 5 years ago. That means they don’t reflect the effectiveness of the newest treatments — and treatments are improving every year.
It’s also worth noting that survival rates for metastatic cancer are very diverse and dependent on the individual and the type of cancer they have. For example, people with hormone-receptor positive cancers and HER2-positive breast cancers may do well for a long time, compared to those with triple-negative breast cancers. So, lumping all forms of metastatic cancer into one statistic can be misleading.
Regardless of the type of breast cancer you have, early diagnosis and treatment are crucial, as survival rates are higher in the early stages of breast cancer. And remember, the right treatment for stage 4 breast cancer can improve quality of life and longevity.