The bones are one of the most common parts of the body where breast cancer cells spread. It’s possible for breast cancer to travel to any bone in the body, but the spine, hips, skull and long bones in the arms and legs are where it’s most often found. Breast cancer in the bones – called bone metastases – can lead to weak bones, pain and a higher risk of fractures. But there are many treatments available for you.
Adults have 206 bones in their bodies. These bones may seem solid and unchanging, but in reality, the cells that make up healthy bones are breaking down and building back up constantly. Bones are made up of three types of cells:
- osteoclasts, which break bones down
- osteoblasts, which repair bones
- osteocytes, which are mature bone cells
When breast cancer spreads to your bones, the cancer interrupts the natural process of bone cells. This can lead to weak bones, pain and a higher risk of fractures.
Bone metastases are areas of cancer that can develop when breast cancer cells travel to the bones. The tumors that develop, sometimes called “lesions,” can
- make the bones weaker and less dense. These types of tumors are called osteolytic, or simply lytic.
- make the bones more dense, but not necessarily stronger. These types of tumors are called osteoblastic, or simply blastic.
It’s common for people to have both bone metastases that make the bones denser and bone metastases that make the bones less dense at the same time.
For many people with metastatic breast cancer, the bones are the first place cancer spread. Almost 70 percent of those with metastatic breast cancer develop bone mets at some point and people with estrogen receptor-positive metastatic breast cancer are more likely to have bone mets than people with other types of metastatic breast cancer. There is no evidence that people of certain ages or ethnicities are more likely to have cancer spread to the bone than others.
Often, first signs of bone metastases are aches and pains that are strong and unexplained. These pains can be caused by the metastases themselves, or by a bone break or fracture.
It can be hard to know when a new ache is cancer-related. These symptoms may not immediately seem like cancer because there are many health issues that cause aches and pains, such as menopause, breast cancer treatments like aromatase inhibitors, or diseases like arthritis. And there are many ways to break or fracture even the strongest bones.
A more serious symptom of bone metastasis is spinal cord compression. Numbness in your arms, legs, hands or feet, trouble urinating and feeling more constipated are signs of spinal cord compression. In spinal cord compression, a dangerous amount of pressure is put on your spinal cord, a bundle of nerves that sends signals from your brain to your muscles. It can be very painful, affect your height and posture, and if not treated can sometimes lead to paralysis, the inability to move.
If you have those symptoms, call your doctor right away. Spinal cord compression is not common, but it is a medical emergency. It is typically treated with radiation therapy, and sometimes also surgery.
If you have a history of breast cancer, even if it was years ago, you should report any bone pain that lasts 4 weeks or more, or that makes you feel you need to see a chiropractor, to your healthcare team. They can help you find out if you’re experiencing metastatic breast cancer symptoms, side effects related to breast cancer treatment, or something else.
Most cases of metastatic breast cancer to the bones are diagnosed after a person tells their doctor about bone-related symptoms. Others are diagnosed when a routine follow-up test suggests something is wrong. If a doctor thinks you may have bone metastases, he or she will order one or more tests to confirm the diagnosis.
Doctors use imaging tests to create pictures of the bones and learn whether cancer has spread to them. These tests include
- Bone scans
- Bone x-rays. These tests can show breaks and other changes in bone structure caused by bone metastases.
- CT scans
- PET scans
Your doctor may also order a blood test, called a blood chemistry test, to check for changes in your blood. Those changes can include high levels of the mineral calcium or of the enzyme alkaline phosphatase. Healthy bodies need calcium and alkaline phosphatase, but too much in your blood could mean tumors in your bones are causing these substances to break down and move to your blood.
Sometimes doctors diagnose bone mets by performing a bone biopsy, in which they use a needle to remove a tiny piece of bone from the suspicious area and test it for cancer cells. If you have just one suspicious area in the bones, or if it’s been many years since you were diagnosed with early-stage breast cancer, your doctor is more likely to recommend a bone biopsy.
If you do have bone metastases, you will have some of these same tests throughout your treatment to monitor the cancer.