Overview
Bone metastasis happens when cancer cells break away from where they started and spread to a bone.
Metastasis is the medical term for disease that spreads to an area away from where it started. When cancer spreads, healthcare professionals say it metastasizes or is metastatic. When cancer cells spread to one spot in a bone, it's called bone metastasis. When there is more than one area of metastasis in the bones, it's called bone metastases.
Bone metastasis is different from bone cancer, also called primary bone cancer. Bone cancer starts in the bone itself. Bone metastasis is cancer that has spread to the bone from another part of the body.
Nearly all types of cancer can spread to the bones. But some types of cancer are more likely to spread to bone. These include breast cancer, prostate cancer and lung cancer.
Bone metastasis can happen in any bone. But it more often happens in the spine, pelvis and thigh bones. Bone metastasis may be the first sign that you have cancer. Or bone metastasis may happen years after cancer treatment.
Bone metastasis can cause pain and bones that break easily. In most situations, there is no cure for bone metastasis. But treatments can help control the cancer, reduce pain and relieve other symptoms.
Types
Bone metastasis can be osteolytic, osteoblastic or mixed.
Osteolytic metastases happen when cancer causes more bone to be broken down than rebuilt. Osteoblastic bone metastases happen when cancer causes atypical new bone to form.
Both osteolytic and osteoblastic metastases can create lesions that can weaken the bone, and some bone metastases have a mixture of both.
Symptoms
Sometimes bone metastasis causes no signs or symptoms.
When symptoms of cancer that has spread to the bone happen, they may include:
- Bone pain. This is the most common symptom. It may feel different depending on where the metastasis is. You may feel pain in one spot, or it may be a more general ache. If nerves are involved, you may feel burning or shooting pain.
- Broken bones. Cancer can weaken bones enough that they can break even with normal activity.
- High calcium levels in the blood, called hypercalcemia. This can cause nausea, vomiting, constipation and confusion.
If bone metastasis is in the spine, it can cause:
- Pain and stiffness in the neck or back from pressure on the spinal cord.
- Weakness in the arms and legs.
- Leaking urine, called urinary incontinence.
- Sudden urge to urinate, called urinary urgency.
- Not being able to control the passing of stool and stool leaking from the bowel, called fecal incontinence.
When to see a doctor
If you have symptoms that last a long time or make you feel worried, schedule an appointment with a doctor or other healthcare professional. If you've been treated for cancer in the past, tell your healthcare team about your medical history and your concern about your symptoms.
New symptoms or symptoms that get worse can mean that cancer has spread to your bones, made a bone weaker or caused other problems. Pain at night that doesn't have a clear cause could be a sign of something serious. Let your healthcare team know right away if your symptoms change.
When to seek emergency care
Seek emergency medical care if you have new weakness or loss of strength, called paralysis, in your arms or legs. Also seek care immediately if you lose control of your bladder or bowels. These symptoms can happen when bone metastasis in the spine puts pressure on the spinal cord.
Causes
Bone metastasis is caused by cancer that starts in one area and spreads to a bone. It's not clear why some cancers travel to the bones rather than to other common sites for metastasis, such as the liver.
Cancer spreads to bones in some common areas. Those include the spine, ribs, pelvis, and upper parts of the legs and arms. Though less common, cancer also can spread to the bones further down the legs and arms, below the knee or elbow.
Risk factors
Anyone with cancer can develop bone metastases, but the risk depends largely on the type and extent of the original cancer. Some types of cancer have a higher risk of causing bone metastasis than others do. The cancers most likely to spread to the bones include:
