What Is a Bone Scan for Cancer?

Bone Scan for Finding Metastases With Cancer

Doctor reading the x-ray in the office
Doctor reading scans in the office. Getty Images/franckreporter

What is a bone scan for cancer? When might this test be recommended? How does it compare with other tests for bone metastases such as a PET scan? And what happens if your scan is abnormal?

Definition: Bone Scan for Cancer

A bone scan for cancer is a nuclear medicine test that looks for abnormalities in bone. An abnormal result on a bone scan may be used to:

  • Detect fractures in a bone: In some cases, such as with some stress fractures or insufficiency fractures, a straight x-ray will not reveal a fracture (or may not reveal a fracture for several weeks) and a bone scan is needed
  • Detect bone diseases such as Paget's disease of bone
  • To look for loosening after hip replacement surgery
  • Detect bone infections: An infection of bone is termed osteomyelitis

Reasons to do a Bone Scan

If your doctor has recommended a bone scan, ask exactly what she is looking for and why she is ordering the test. Some of the reasons a bone scan may be done (for both cancer and benign conditions) include:

  • To evaluate pain in your extremities, ribs, or spine
  • To evaluate an unexpected fracture - When a bone is weakened by the presence of a cancer,  either a primary bone cancer, or cancer metastases to bone, this is referred to as a pathologic fracture 
  • To evaluate abnormal blood tests: For example, if you have increased levels of calcium in your blood (hypercalcemia) or other abnormalities
  • To help diagnose and stage cancers that can spead to bones: A bone scan is often done following a diagnosis of cancer to look for bone metastases. Staging in this setting is needed to determine the most appropriate treatments

The Procedure

During a bone scan, a radioactive tracer (usually Technetium 99m) is injected into a vein in your arm and collects in bone.

After a period of time, usually 3 to 4 hours, a scan is done.The radioactive material that has collected in bone gives off gamma rays that can be picked up with a special camera. The scan itself usually takes about an hour to complete.

Results

A radiologist will then review the scan looking for abnormalities.The scan may be normal, or could instead have either hot spots or cold spots.

"Hot spots" in bone are areas that take up more of the radioactive tracer. These may indicate the presence of cancer, an infection (osteomyelitis), some bone diseases, or arthritis.

"Cold spots" are areas in bone that take up less of the tracer. These can be seen with some forms of cancer such as multiple myeloma and some bone diseases.

Possible Side Effects of a Bone Scan

Though the terms nuclear medicine and radioactive may sound frightening, the procedure is very safe and involves little discomfort other than a needle poke for the injection.

Bone Scans vs PET Scans for Bone Metastases

A common question from people with cancer concerns when a bone scan should be done and when a PET scan should be done. There are several factors to consider and it is important to talk to your doctor about her reasoning for the choice.

Bone scans are significantly cheaper than PET scans, though PET scans can sometimes provide more information and detect metastases that would not be found on a bone scan alone.

Bone Metastases: Which Cancers Spread to Bones?

Common cancers that spread to the bone include lung cancer, breast cancer, thyroid cancer, prostate cancer, and kidney cancer. When cancers spread to bones there are most often multiple metastases.

Location of Bone Metastases

Adult cancers commonly spread to the "axial skeleton" meaning the bones of the spine. Roughly 90 percent of bone metastases occur in a combination of the vertebrae, the pelvis, the skull, the upper leg (the proximal femur) and the upper arm (the proximal humerus.) As noted earlier, there are usually several metastases to bone when these are discovered, and a solitary "spot" suggests that it could be due to something else.

 

Cancer may first be detected by finding bone metastases before the origin of the cancer is found. When this occurs, further evaluation is needed to look for the primary cancer. Sometimes the location of the metastases can lead doctors to suspect where a cancer began. For example, lung cancer is somewhat unique in that it commonly spreads to bones in the hands and feet.

Coping with Abnormal Bone Scan Results

Worrying that a cancer has spread to bones, or finding out that your cancer has spread to your bones can be terrifying. What does that mean now? 

With regard to those with cancer, bone scans can create tremendous scanxiety, a term that has been coined to describe the anxiety often felt while waiting for scan results. If you've recently been diagnosed, your bone scan results could mean that your cancer is stage 4; that it has spread to your bones and surgery is no longer possible. If you've been living with cancer, your first thoughts might be, "how can I again cope with treatments?" 

Talk to friends and loved ones and ask for support. If you have a cancer support group or support community, reach out to them. Often those who have been living with cancer themselves can appreciate much more the anxiety about bone scan results. Here are a few tips on coping with the fear of recurrence or progression of your cancer.

Ask a lot of questions and talk to your oncologist. What treatments would she now recommend? Are there any clinical trials that would be appropriate for you? Keep in mind that treatments for cancer—even advanced cancer—are improving. Newer categories of drugs such as targeted therapies and immunotherapy are sometimes able to control cancers that were previously very difficult to treat. 

Treatment of Bone Metastases

If you are diagnosed with bone metastases, you may be treated with general treatments for metastatic cancer but bone-specific treatments are also available. In some cases, such as with breast cancer, these treatments can not only reduce pain and fracture risk from bone metastases but increase life expectancy as well.

Learn more about bone metastases with lung cancer and bone metastases with breast cancer.

Sources:

Thomas, K., and M. Gould. Overview of the Initial Evaluation, Diagnosis, and Staging of Patients with Suspected Lung Cancer. UpToDate. Updated 04/05/17. http://www.uptodate.com/contents/overview-of-the-initial-evaluation-diagnosis-and-staging-of-patients-with-suspected-lung-cancer

U.S. National Library of Medicine. MedlinePlus. Bone Scan. Updated 08/16/17. https://medlineplus.gov/ency/article/003833.htm

Also Known As: Bone Scintigraphy

Examples: James was having pain in his neck after he had surgery for his lung cancer, so his oncologist recommended a bone scan to see if his cancer had spread to his spine.

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