The most common site for bone metastases is the vertebra. Although it also occurs in long bones, pelvis, ribs, sternum, and skull.

Complications of bone metastasis are called skeletal-related events (SREs) and include most commonly bone pain, pathologic fractures and hypercalcemia, and less commonly nerve root or spinal cord compression.

Spine Instability Neoplastic Score (SINS) can help determine the need for a surgical referral based on stability of pathologic spinal fractures.

• Breast, prostate, and lung cancer make up near 80% of bone metastases.
  • Also kidney, lymphoma, multiple myeloma, thyroid.
• Bone pain attributed to metastases is the principal source of cancer-related pain and can severely impact quality of life.

Clinical Presentation

 

 

 

 

History

• Cancer diagnosis or features that suggest malignancy if no prior diagnosis (ie: unintentional weight loss, fatigue, drenching night sweats – B Symptoms).
• If cancer diagnosis available:
  • Primary cancer.
  • Known mets.
  • Current treatment (chemo, radiation, next treatment, last treatment).
  • Principle oncologist.
  • Patients’ Medical Orders for Scope of Treatment (MOST) status.

SREs

• • Bone pain:
    • Typically gradual onset of non-traumatic, dull, aching pain that worsens at night.
  • Pathological Fracture:
    • Present clinically as a fracture with no history of trauma or only minor trauma.
  • Hypercalcemia:
    • Renal stones, psychosis, abdominal pain, constipation, polyuria, polydipsia (Stones, bones, abdominal groans, thrones and psychiatric overtones – rarely seen).
    • Spinal cord compression:
      • Urinary retention, incontinence of stool, weakness in upper or lower limbs, sensory changes in upper or lower limbs.

Investigations in the ED

• Imaging: High-risk fracture features for the potential to develop a pathological fracture include painful lesion, >2.5cm in size and >50% of the bone is involved.
  • Xray: useful but misses less severe bone metastases.
  • CT: more sensitive (74%).
  • MRI: 95% sensitivity and 90% specificity for bone metastases and can also detect cord compression (6).
• Specific labs: CBC, Cr/GFR, Calcium, ALP, Serum Protein Electrophoresis (SPEP), UPEP, ECG.

Differential diagnosis

• Benign bone tumor.
• Malignant bone tumor.
• Infection (osteomyelitis).
• Trauma.
• Osteonecrosis.

Table 1. Imaging Characteristics of Bone Metastases

Emergency treatment:

• Bone pain

  • Initial trial with NSAIDs and acetaminophen with step-up to opioids as needed in the setting of acute pathologic fractures and associated pain.

• Hypercalcemia

  • IV fluids are the key.
  • Ensure adequate renal function.
  • May initiate bisphosphonate therapy in ED if severe hypercalcemia and cardiac instability.
    • Alternately zoledronic acid 4mg IV over 15mins or pamidronate 60 – 90 mg IV over 2 hours.
  • Moderate asymptomatic hypercalcemia can treated with fluids and calcitonin 4 IU/kg IV.

• Inpatient vs outpatient decision based on:
  • Unstable fractures.
  • Extent of metastases.
  • Spinal cord compromise.
  • Referral to specialists (surgery and oncology).

1. Epidemiology, clinical presentation, and diagnosis of bone metastasis in adults
   Yu M, Hoffe S. 2019 [cited 2019 May 8].
   UpToDate [Internet].

   
   

2. Spinal Instability Neoplastic Score: An Analysis of Reliability and Validity From the Spine Oncology Study Group.
   Fourney DR, Frangou EM, Ryken TC, Dipaola CP, Shaffrey CI, Berven SH, et al.  2011 Aug [cited 2021 Apr 10];29(22):3072–7. 
   J Clin Oncol [Internet]

   
   

3. A Novel Classification System for Spinal Instability in Neoplastic Disease From the Spine Oncology Study Group.
   Fisher CG, DiPaola CP, Ryken TC, Bilsky MH, Shaffrey CI, Berven SH, et al. (October 15, 2010 – Volume 35 – Issue 22 – p E1221-E1229)
   *Combined Neurosurgery and Orthopaedic Spine Program

   
   

4. Managing skeletal related events resulting from bone metastases.
   Wilkinson AN, Viola R, Brundage MD.  Vol. 337, 2008. p. 1101–5.
   The BMJ.

   
   

5. Mechanisms of Bone Metastasis [Internet].
   David Roodman G.  Vol. 350, 2004 [cited 2019 May 2]
   N Engl J Med.

   
   

6.  Bone metastasis. In: Functional Imaging in Oncology: Clinical Applications – Volume 2 [Internet].
   Jayarangaiah A, Kariyanna PT. Springer Berlin Heidelberg; 2014 [cited 2021 Apr 10]. p. 1389–410. NCIB