Metastatic Cancer involving Long Bones

1. Pathophysiology: Cancers most prone to metastasize to long bones
   1. Most common cancers with bony metastases
      1. Breast Cancer
      2. Prostate Cancer
   2. Other common cancers with bony metastases
      1. Lung Cancer
      2. Renal Cancer
      3. Thyroid Cancer
2. Symptoms
   1. Localized bone pain
   2. Dull, Intermittent pain
      1. Night pain and rest pain is pathognomonic for Cancer Pain
      2. Pain despite lack of injury history
      3. Weight-bearing related pain may predict Fracture
3. Exam
   1. Focus on identifying primary cancer if not known
4. Imaging
   1. General
      1. Multiple lesions are hallmark of metastatic bone cancer
   2. Plain film XRay: Indicated as first-line study
      1. Efficacy
         1. Test Sensitivity: Low (requires 50% Trabecular Bone loss before evident)
         2. Test Specificity: Highest among imaging studies
      2. Findings
         1. Lytic lesions: Lung Cancer, Thyroid Cancer, Renal Cancer
         2. Blastic lesions: Prostate Cancer
         3. Other cancers are mixed-type (lytic and blastic)
   3. Bone Scan
      1. Indications
         1. Identify additional metastatic cancer sites
         2. Evaluate bone pain in patient with known primary tumor
      2. Efficacy
         1. Test Sensitivity: High
            1. Identifies bony lesions down to 2 mm
            2. Identifies metastatic lesions up to 18 months before plain film xray
         2. Test Specificity: Low
   4. Computed Tomography (CT Scan)
      1. Indications
         1. Identify primary tumor site (CT chest, Abdomen and Pelvis)
         2. Evaluate bony cortex destruction
         3. Evaluate periarticular joint destruction
   5. Magnetic Resonance Imaging (MRI)
      1. Indications
         1. Evaluate spinal lesions
         2. Evaluate soft tissue spread of bony lesions
         3. Evaluate Bone Marrow destruction
   6. References
      1. Rosenthal (1997) Cancer 80:1595-607 [PubMed]
5. Labs: Adjust based on primary tumor suspected
   1. Serum Protein Electrophoresis (SPEP)
      1. Evaluate for Multiple Myeloma
   2. Complete Blood Count with platelets
      1. Evaluate for Anemia and Thrombocytopenia
   3. Serum Creatinine
   4. Serum Calcium
      1. Evaluate for Hypercalcemia
   5. Serum Alkaline Phosphatase
   6. Prostate Specific Antigen (PSA)
6. Labs: Biopsy Indications
   1. Confirm metastatic cancer in known primary cancer
   2. Evaluate bone tissue for advance lab testing (e.g. immunohistochemical stains)
   3. Evaluate bony lesion where primary tumor is unknown
      1. Rarely identifies the primary tumor
7. Management
   1. Pain management
      1. Narcotic Analgesics
      2. NSAIDs
      3. Corticosteroids if nerve impingement from tumor mass
   2. Suppression of tumor growth or mass effect
      1. Calcitonin does not appear effective in reducing pain, morbidity, or cancer progression
      2. Bisphosphonates (started when bony metatastases are diagnosed)
         1. Pamidronate (Aredia) 90 mg IV every 3 weeks or
            1. Lipton (2000) Cancer 88:1082-90 [PubMed]
         2. Zoledronic acid (Zometa)
            1. Rosen (2004) Cancer 100:36-43 [PubMed]
      3. Chemotherapy
         1. Cancer-specific agents
         2. Hormonal therapy: Breast Cancer, Prostate Cancer
      4. Radiotherapy or Radiopharmacotherapy
      5. Surgical intervention indications
         1. Impending pathologic Fracture
         2. Decrease pain
         3. Improve morbidity and function
8. References
   1. Hage (2000) Orthop Clin North Am 31:512-28 [PubMed]
   2. Riccio (2007) Am Fam Physician 76:1489-94 [PubMed]