When breast cancer metastasizes (spreads), it can spread to the bones. Metastatic breast cancer is also known as stage 4 (sometimes written with Roman numerals: stage IV) breast cancer. More than 50 percent of people with stage 4 breast cancer experience cancer spreading to the bones.

It’s important to be aware of the symptoms of bone metastasis if you’ve received a breast cancer diagnosis. Knowing what to watch out for could help you find signs of spread early. Several therapies can help slow or stop the spread of cancer as well as help treat symptoms.

The idea of breast cancer spreading to other parts of the body is stressful, especially because metastatic cancer doesn’t always cause symptoms. Make sure to tell your oncologist if you notice any health changes, including the following signs and symptoms that could suggest breast cancer spreading to the bones.

1. Bone Pain

Cancer cells are more likely to spread to some bones than others. One of the most common sites of bone metastasis is the spine, which can lead to back pain. Hip pain caused by cancer cells growing in the pelvic bones or femur (thigh bone) is also common. Bone pain may affect other areas of the body, such as your ribs.

At first, bone pain caused by metastasis may come in waves. You may have to live with pain for a short period and then feel better. Eventually, the pain will occur more often until it no longer goes away. This pain also tends to get worse at night.

Bone pain in breast cancer can have other causes like arthritis or osteoporosis, or it can be a secondary effect of chemotherapy. Your healthcare team can help identify and manage any pain.

2. Broken Bones

If you suddenly feel intense pain and can’t move a particular part of your body, you may have a pathologic fracture (a broken bone that occurs due to another condition that has weakened the bone’s structure). The fracture happens not because of a significant trauma but because the spreading cancer weakens the bone. Other symptoms of a broken bone include numbness, weakness, swelling, bruising, or tenderness when you touch the area. A pathologic fracture is a medical emergency, so it is important that you inform your healthcare team if you feel sudden intense bone pain.

3. Leaking Urine

Urinary incontinence occurs when you unintentionally leak some urine. For people with breast cancer, this may be a sign of metastasis to the spinal cord. Your spinal cord is a bundle of nerves that runs from your brain down your spine. If breast cancer spreads to your vertebrae (the bones of the spine), one vertebra may break and press against your spinal cord, leading to spinal cord compression and various symptoms.

Urinary incontinence isn’t always a symptom of breast cancer metastasis. It can also occur due to urinary tract and vaginal infections, diabetes, arthritis, Parkinson’s disease, or medications. In general, urinary incontinence is more common in older adults. However, tell your oncologist if you experience this as a new symptom while living with breast cancer.

4. Inability To Control Bowel Movements

Another sign of breast cancer spreading to bones is bowel incontinence — loss of bowel control. Bowel incontinence can also occur because of spinal cord compression. This symptom may cause stool to come out when you don’t want it to. On the other hand, spinal cord compression may also make it more difficult to go to the bathroom.

5. Other Symptoms of Spinal Cord Compression

About 95 percent of people with spinal cord compression report having pain in their neck or back. Spinal cord compression can also lead to other issues, including nerve pain in your buttocks or legs, limping, an inability to have sex, or numbness and weakness in a certain part of your body, such as your hand, leg, or abdomen.

Spinal cord compression needs to be treated right away. It can worsen quickly and may lead to paralysis. Contact your healthcare provider or go to the emergency department if you have breast cancer and think you may be having signs of spinal cord compression.

6. High Calcium Levels

Tumors in your bones can cause your bone tissue to break down. More than 99 percent of calcium is stored in bones. When bones get damaged or weak, they release some of this calcium into the blood.

High levels of calcium in the blood, known as hypercalcemia, can lead to additional symptoms, such as:

• Upset stomach
• Nausea or vomiting
• Loss of appetite
• Constipation
• Extreme thirst or increased urination
• Heart palpitations (irregular heartbeat)
• Tiredness or weakness
• Confusion
• Depression

Hypercalcemia can be detected with a simple blood test.

Treatments for Bone Metastasis

If there is a chance you have bone metastases, your doctor may recommend additional tests for diagnosis, including an X-ray, a bone scan, a CT scan, or an MRI. They may also do a biopsy (take a sample of the bone for laboratory testing).

Several treatment options can kill cancer cells in your bones, strengthen your bones, and reduce symptoms to help you feel your best when living with metastatic breast cancer.

Cancer-Killing Treatments

Targeted therapy drugs can help treat bone metastases if your cancer cells contain certain gene or protein changes. HER2-positive cancer (breast cancer that contains high levels of a protein called HER2) can often be treated with medications like trastuzumab (Herceptin) or pertuzumab (Perjeta). Additionally, breast cancer cells that contain estrogen receptor (ER) or progesterone receptor (PR) can be treated with other targeted therapies like everolimus (Afinitor) or palbociclib (Ibrance).

Targeted therapy drugs are often given as part of a treatment plan together with chemotherapy, a common treatment for metastatic breast cancer. Additionally, hormone therapy may help treat bone metastases if your breast cancer is ER- or PR-positive. Hormone therapy paired with a CDK4/6 inhibitor (cancer drugs that target certain enzymes) is often recommended for most hormone receptor-positive metastatic cases because this combination has been shown to slow down the progression of the disease and improve survival rates. CDK4/6 inhibitors include palbociclib, ribociclib (Kisqali), and abemaciclib (Verzenio).

There have also been advances in treating metastatic triple-negative breast cancer (TNBC). Pembrolizumab (Keytruda) combined with chemotherapy is FDA-approved as a first-line treatment for PD-L1-positive metastatic TNBC. Antibody-drug conjugates (ADCs) like sacituzumab govitecan-hziy (Trodelvy) attach to a protein and deliver chemotherapy directly to the cancer cells. This ADC is used to treat advanced TNBC when first-line treatments have failed. In addition, datopotamab deruxtecan-dlnk (Datroway), another ADC, improved survival rates in clinical trials and is on track for FDA approval as a first-line treatment for PD-L1-negative (low levels of PD-L1 proteins) TNBC.

Other cancer treatments, like radiation therapy or surgery, may also help if you have only a small number of metastases.

Bone-Strengthening Treatments

Two types of medications can make your bones stronger, reducing your risk of fractures and other serious problems if you have bone metastases.

Bisphosphonates such as pamidronate disodium (Aredia) and zoledronic acid (Zometa) slow down and prevent bone loss. Another option is the RANK ligand inhibitor denosumab (Xgeva). This medication prevents osteoclasts (cells that break down bone) from dissolving too much bone tissue. Denosumab is given as a subcutaneous (just under the skin) injection about every four weeks.

These treatments can reduce the likelihood of bone fractures and hypercalcemia. They can also ease pain and stop bone metastases from growing bigger. However, in some cases, they cause a rare side effect called osteonecrosis of the jaw, in which part of the jawbone dies. If you need bone-strengthening drugs, your doctor may recommend getting any necessary dental work before starting them.

Treatments To Relieve Symptoms

Bone pain can be treated with different types of painkillers. Over-the-counter options such as ibuprofen and acetaminophen may be enough to ease mild aches and pains. However, ask your doctor before taking these, as you might need to stay away from certain medications if you have heart failure or kidney disease.

You may be able to take stronger painkillers if you have severe pain. Your doctor may prescribe opioids like morphine or oxycodone for pain relief, which may lead to nausea, fatigue, or constipation. Steroid medications can also ease pain and swelling.

Treatments often used to kill cancer cells — such as radiation, chemotherapy, and hormone therapy — may also help relieve symptoms. Most people receive external-beam radiation or stereotactic radiation directed at painful sites to relieve symptoms and control the disease.

Radiopharmaceuticals (medications that contain a small amount of radioactive material) may relieve bone pain in selected cases of people with multiple unresponsive tumors. Targeted radionuclide therapy (TRT) involves injecting a radioactive chemical (such as strontium-89 or samarium-153 lexidronam) through a vein as a one-time dose to relieve pain.

Ablation is a technique that uses extreme heat, freezing temperatures, or electrical currents to destroy or shrink tumors in the bone. This approach can help relieve pain caused by metastasis.

Your doctor may also recommend surgery to fix a broken bone or strengthen a bone that’s at risk of breaking. Doctors can use metal plates, screws, or bone cement to stabilize your bones.

Physical therapy can also help you build strength and flexibility and allow you to move around more easily. This treatment may help you better manage or prevent pain and improve your quality of life.

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