Description

• The skeleton is one of the most common sites for metastatic cancer.
• Bone metastasis can cause significant morbidity including pain, pathologic fractures, spinal cord compression, and hypercalcemia.
  • 80% of bony metastasis are due to breast, prostate, and lung cancers (1).

Epidemiology

Incidence

• Breast cancer—73% bony metastasis
• Prostate—68%
• Thyroid—42%
• Lung—36%
• Renal—35%
• Melanoma—35% (2)

Prevalence
Not well understood

• Approximately 1.2 million new cancer diagnoses in the United States each year
• Approximately 300,000 total cases of metastatic bone disease in the U.S. population in 2008 (3,4)

Etiology and Pathophysiology

• Types of bone metastasis
  • Osteolytic—thyroid, non–small cell lung, kidney, multiple myeloma
  • Osteoblastic—prostate, small cell lung
  • Mixed—breast, cervical, ovarian, testicular
• Bone—specifically the axial skeleton—is a common site for metastasis due to high blood flow in the red marrow.
• Tumor cells exhibit adhesive molecules that allow them to bind stromal cells in the bone marrow.
• Tumor cells produce factors that stimulate osteoblastic and/or osteoclastic activity leading to disruption in bone remodeling (2)[A].

Genetics

• Studies are ongoing to identify specific genes involved in bony metastasis.
• 5–10% of all cancers are hereditary.
  • Most common type is hereditary breast and ovarian cancer syndrome caused by mutations in BRCA1 or BRCA2 (4).

Risk Factors

• Advanced disease
• Late presentation to care
• Large tumor size
• Poorly differentiated tumor
• Breast cancer is the most likely culprit for bony metastasis in the United States.

General Prevention

• Prevention of primary tumor/early detection
• Timely mammogram evaluations
• Cervical Pap smears
  • Prostate-specific antigen (PSA) per guidelines—strong family history
  • Colonoscopy

Commonly Associated Conditions

• Bone pain
• Pathologic fractures
• Hypercalcemia
• Nerve compression
• Spinal cord compression
• Cauda equina syndrome