Bone Scan for Prostate Cancer

Beyond the lymph nodes, the next most common site of metastasis in prostate cancer is the bone, and can be a significant concern for those with advanced prostate cancer, affecting over 90% of metastatic prostate cancer cases. Compared to all other cancers, prostate cancer patients are at the highest risk of developing cancer spread to the bone. Therefore, the ability to identify and treat bone metastasis as early as possible is critical to preserve one’s quality of life and chances of survival for those with advanced prostate cancer.

Generally, the bones of the axial skeleton (the central core of your body), are the most likely affected by prostate cancer metastasis. This includes the skull, neck, back, and ribcage. The symptoms of prostate cancer that has spread to the bones include bone pain (e.g. dull aches which become more severe at night, and may become piercing at times), the risk of bone fracture due to weakened bones, and spinal cord compression. In particular, spinal cord compression is a severe issue that requires immediate medical attention. It may surface as difficulties in walking, back pain and weakness or numbness in your limbs.

The bone scan, also known as bone scintigraphy, is an imaging scan that helps visualize abnormalities in the bones with the help of a radioactive tracer, usually technetium-99m diphosphonate. This imaging test is affordable and accessible to many, and thus most commonly used for identifying bone metastasis in cases of intermediate-risk and high-risk prostate cancer. Additionally, you will not need to fast or undergo anesthesia for the bone scan. However, you will likely need to remove jewelry or other objects that may interfere with the scan.

Radioactive tracers are developed for the bone scan by attaching the radioactive molecule, technetium-99m, to disphosphonates, molecules which mimic the phosphate found in bone mineral. Once injected, this allows the radioactive tracers to attach easily to the bone, especially in areas with high levels of bone formation, typically indicative of cancerous activity. This can take around one to three hours. To ensure a clearer visualization, you may be advised to drink a few cups of water to help flush out the remaining radioactive tracers which do not attach to the bone. Finally, once visualized by a scanner, the radioactive tracers will emit gamma radiation that can help highlight areas likely to have cancerous tissue.

The radioactive tracer used for the bone scan emits very low levels of radiation, so no precautions will be required to protect against radioactive exposure. However, you may be advised to drink lots of water for the next 24 to 48 hours and to urinate often, in order to flush out all the remaining tracer in your body. There is a small risk of allergic reactions to the radioactive tracer. If you have known sensitivities to medications, contrast dyes or iodine, you should let your doctor know.