Bone Pain

Management

Bone pain is usually caused by cancer metastases to bone (80% of which occur secondary to breast, prostate or lung cancer). Painful bone metastases frequently give rise to incident pain or pain on movement. Pain is described as dull, aching, constant and worse with movement and weight-bearing activities. It may be localised to the area of infiltration or referred pain if there is compression of nerves. 

Pain frequently caused by pathologic fracture. 

Management 

1. WHO step 1/2/3 analgesics 
   • NSAIDs are considered first-line therapy for bone pain, if there are no contra-indications to these, although evidence for this practice is limited. 
   • Opioids: since most patients experience moderate to severe pain, opioid analgesics are frequently needed. 
   • Additional doses of opioid (± 15% of total daily dose) are frequently required for incident pain caused by bone metastases. 
2. Radiotherapy is effective & recommended therapy for symptomatic bone metastases 
   • 41-90% patients experience partial relief of bone pain, following radiotherapy, with 25-50% having complete relief. 
   • The full extent of pain relief, however, can take 3-4 weeks. 
   • Single fraction radiotherapy is well-tolerated & convenient. Multiple fractions may sometimes be indicated. Half-body radiation is used for disseminated bone metastases, but has significant side effects. 
   • Not indicated in patients who are very weak or who have very limited life expectancy. 
3. Surgical interventions 
   • Stabilisation of osteolytic lesions by fixation with pins & plates, injection of bone cements & fusion of vertebrae 
   • Laminectomy to relieve pressure on spinal nerves 
4. Chemotherapy & hormone therapy, specific for the malignancy resulting in the bone metastases (in conjunction with oncologist). 
5. Bisphosphonates (osteoclast inhibitors) 
   • Pamidronate 90mg IV infusion (diluted in 500ml normal saline) & infused over 2-4 hours or Zoledronic acid 4mg IV infusion over 15 minutes. 
   • Can be used as part of a long term strategy to reduce skeletal complications, including pain from bone metastases. In this case, bisphosphonates are initiated at first diagnosis of bone metastases (irrespective of symptoms) & administered every 3-4 weeks. 
   • Also indicated to relieve metastatic bone pain as an adjunct to analgesics, radiotherapy or surgery. 
     • Bisphosphonate analgesic effect within 14 days 
     • If no response, can repeat after 2 weeks 
     • Failure to respond after 2 treatments makes further treatment inappropriate 
     • If good response, consider regular bisphosphonates every 3-4 weeks 
   • Prolonged bisphosphonate therapy may be complicated by osteonecrosis of the jaw, which is difficult to treat. This occurs especially in patients with poor oral dentition. Patients should be advised to maintain good oral hygiene & have regular dental check- ups, while on this therapy. 
   • Use with caution in patients with renal impairment. 
6. Corticosteroids
   • Not used routinely. 
   • May be used in patients with diffuse bone pain with an inadequate response to analgesics and other treatment modalities. 
   • Especially useful in patients with neurological symptoms due to spinal cord compression 
7. Muscle relaxants for associated muscle spasm. Baclofen is preferred to diazepam and dantrolene, which have more side effects. 
8. Radio isotope therapy for disseminated bone metastases – not widely used.