A bone scan, also called bone scintigraphy, is an imaging test used to determine whether breast cancer has traveled to the bones. Your doctor may order a bone scan:
- at initial diagnosis, to make sure your bones are healthy, as well as to create a set of “baseline images” that could be compared to any future bone scans that are done
- during and after treatment, if you experience persistent bone and joint pain, or if a blood test suggests the possibility that the breast cancer has traveled to the bones
Bone scans begin with an injection of radioactive material into your arm, which will be taken up by the body’s bone-making cells over the next few hours. These bone-making cells are found mostly in areas damaged by disease, where they are busily trying to make new bone to patch the holes. After waiting 2 to 4 hours for the radioactive substance to be absorbed, the doctor uses a special camera to scan the body. Areas of extra bone activity (common in both cancer and arthritis) will show up on the scan because the radioactive substance collects in areas of new bone formation. These areas appear as dark patches on the film. Any part of the bone can be affected by cancer.
Except for the needle stick to give the injection, a bone scan is painless, although it may require you to lie still for up to an hour while the scanning is done. The test involves very little radiation exposure and poses no greater risk than a standard x-ray.
Many changes that show up on a bone scan are not cancer. With arthritis, the radioactive material tends to show up on the bone surfaces of joints, not inside the bone. But it can be hard to tell the difference between arthritis and cancer — especially in the spine. That’s because the spine is made up of so many little bones and joints. Changes in the spine may require additional evaluation.
Talk to your doctor about whether he or she recommends bone scans for your particular situation. You will not need bone scans if you’ve been diagnosed with a non-invasive form of breast cancer, such as ductal carcinoma in situ (DCIS). Typically there is no need to have yearly follow-up bone scans if you aren’t experiencing any unusual symptoms, such as persistent pain. The exam is expensive and time-consuming, and studies have shown that it won’t improve your quality of life or length of survival. Yet if you’re experiencing persistent back or leg pain, a repeat bone scan that shows no change from the baseline study is usually reassuring. Back pain is a common problem, but if you’ve had breast cancer it can cause a great deal of anxiety.
Keep in mind that a bone scan is a different test than a bone density study (such as DEXA), which evaluates bone strength and your risk of osteoporosis (thinning of the bones).