Diagnosis and Monitoring of Bone Metastases

Reducing or delaying bone complications can improve patients’ outcomes.[1] Routine assessment may help maintain bone health.

	ZOMETA Efficacy Bone Health Nurse Program Benefits in Treating Bone Metastases

In 2003, the American Society of Clinical Oncology updated the guidelines on the role of bisphosphonates in women with breast cancer.[2]

The ASCO panel concluded that oncology professionals, especially medical oncologists, need to take an expanded role in the routine and regular assessment of women with breast cancer.[2]

Bone metastases may mimic other skeletal diseases. Pathologic fractures may be the first sign of occult cancer. Early identification and attention to bone metastases can help proper treatment. Bone metastases may manifest themselves as pain, which may often be described as generalized deep pain, radiating pain, tingling, numbness, achy bones, or muscles pain—including back pain. Bone metastases can be detected and monitored in several ways:

• Skeletal Radiograph
• Bone Scan
• Computed Tomography (CT)
• Magnetic Resonance Imaging (MRI)

Skeletal Radiograph

This method will identify the net result of bone resorption and repair. However, for a destructive lesion in trabecular bone to be recognized on a plain radiograph, it must be greater than 1 cm in diameter with a loss of approximately 50% of the bone mineral content.[3]

Bone Scan

The bone scan reflects the metabolic reaction of bone to the disease process, whether neoplastic, traumatic or inflammatory. When bone metastases develop, blood flow and reactive new bone formation usually increase sufficiently to produce a focal increase in tracer uptake, often before bone destruction can be seen radiologically. Scintigraphic and radiographic appearances therefore do not necessarily correlate, although most comparative studies have found the bone scan to be more sensitive.[4]

Metastases appear in bone scans as multiple, irregularly distributed foci of increased tracer uptake that do not correspond to any single anatomic structure. Although bone metastases are usually multiple when diagnosed, up to 20% of women with breast cancer present with a solitary hot spot on the bone scan with or without pain.[5]

Computed Tomography (CT)

CT produces images with excellent soft tissue and contrast resolution. Bony destruction and sclerotic deposits are well shown and any soft tissue extension of bone metastases clearly demonstrated. CT is most appropriate for diagnosing spinal metastases, but as the whole spine cannot readily be scanned, it is normally reserved for assessment of patients with positive bone scans and negative radiographs in an attempt to clarify the pathology.[6]

Magnetic Resonance Imaging (MRI)

MRI has the advantage over CT of providing multiplanar images. The solid constituents of cortical bone give no signal on MRI and appear black, while the high water content of fat and bone marrow results in strong signals and a white appearance. Detection of bone metastases by MRI depends on differences in MR signal intensity between tumor tissue and normal bone marrow. Metastatic tumor is, therefore, visualized directly, in contrast to the indirect changes observed by radiograph or radionuclide bone scanning.[10]

1. Major PP, Cook R. Efficacy of bisphosphonates in the management of skeletal complications of bone metastases and selection of clinical endpoints. Am J Clin Oncol. 2002; 25:S10-8.
   
2. Hillner BE, Ingle JN, Chlebowski RT, et al. American Society of Clinical Oncology 2003 Update on the role of bisphosphonates and bone health issues in women with breast cancer. J Clin Onco l 2003 ; 21: 4042-4057. Accessed September 22, 2005 at: http://www.jco.org/cgi/content/full/21/21/4042.
   
3. Edelstein GA, Gillespie PJ, Grebbel FS. The radiological demonstration of osseous metastases: experimental observations. Clin Radiol. 1967;18:158.
   
4. Fogelman I, Coleman RE. The bone scan and breast cancer. In Freeman L, Weissman H (eds). Nuclear Medicine Annual. New York, NY: Raven Press;1988:1.
   
5. Boxer DI, Todd CEC, Coleman R, Fogelman I. Bone secondaries in breast cancer: the solitary metastasis. J Nucl Med. 1989;30:1318.
   
6. Rubens RD, Coleman RE. Bone metastasis. In: Abeloff MD, Armitage JO, Lichter AS, et al eds. Clinical Oncology. New York, NY. Churchill Livingstone: 1995:643-648.