Cells can break off from your original tumors and travel through your blood and lymph system into other parts of your body. When you have breast cancer, it often first spreads to your bones. This is called bone metastasis, and may cause severe pain and a decrease in your quality of life.
Once affected by cancer, your bones can quickly lose calcium and cause hypercalcemia, a condition in which calcium is released into the blood. If not treated, hypercalcemia may lead to coma and kidney damage. The loss of bone calcium is particularly serious for older women, who have naturally weaker bones.
Bone metastasis is serious, but treatment can help stop further damage to your bones and improve your symptoms. Medications, other cancer therapies such as radiation, and taking steps to prevent falls may ease your pain and protect your skeleton.
Symptoms Point to Cancer's Spread
Bone metastasis may not have any symptoms. But often, you'll feel pain in your bones. The ache may come and go and first, often worsening at night and easing up when you're active. Eventually it can become more intense and flare during activity.
If you have hypercalcemia, you may have other symptoms as well, including:
Sometimes a fracture in your arms, legs, or spine is the first sign that your cancer has spread. You may break a bone when you fall or incur another injury, or during your regular daily activities. If you do, you'll feel sudden, severe pain. Get immediate treatment—especially if the pain strikes in your back, a sign of a broken bone in your spine.
Tests Detect Tumors in Your Bones
Your doctor may check you for bone metastasis if you have these signs, or if you have certain risk factors, including larger tumors or later-stage cancer. Tools he or she may use to make the diagnosis include:
Imaging tests, including X-rays, bone scans, magnetic resonance imaging, and computed tomography scans
Blood tests to check for high calcium levels or other chemicals that indicate your cancer has spread
Urine tests, which can find substances that are released when bone is damaged
Biopsies, when your doctor takes a sample of your tissue and looks at it under a microscope
When your doctor tells you the stage of your breast cancer, he or she will use three letters: T (for the extent of the main tumor), N (to indicate whether it has spread to nearby lymph nodes), and M. The "M" category describes whether your cancer has spread to distant parts of your body. If you have bone metastasis, your cancer is in stage M1.
Treatment Often Involves Medications
If your doctor finds bone metastasis, you will most likely be treated with a type of medication called a bisphosphonate. This drug is given through an intravenous (IV) line.
Here's how bisphosphonates work:
They inhibit further bone damage. This includes thinning bones caused by other treatments for breast cancer, such as hormone therapy.
They reduce common symptoms and high blood calcium levels.
They help prevent complications of bone metastasis, such as pain and bone breaks.
Your doctor will most likely tell you to take vitamin D and calcium in addition to bisphosphonates. This prevents your calcium level from dropping too low.
A newer drug called denosumab (Xgeva, Prolia) also prevents fractures and may strengthen your bones. Other treatment options include chemotherapy, radiation, and surgery. These may be used with bisphosphonates, in other combinations, or separately. Your cancer care team will help you choose the best treatment plan for your cancer and bone metastasis.