Makindo Medical Notes

🦴 Metastatic bone disease has a major impact on patient morbidity and mortality. Bone is the 3rd most common site of metastasis (after lung and liver).

ℹ️ About

• 📊 Common in advanced stages of breast, prostate, lung and other cancers.
• 🎯 Management is aimed at pain control, fracture prevention, spinal stability and prolonging survival.

⚠️ Causes (Primary Tumours that Spread to Bone)

• 🫁 Lung cancer
• 🎗️ Breast cancer
• ♂️ Prostate cancer
• 🦋 Thyroid carcinoma
• 🩸 Renal cell carcinoma
• 🧬 Lymphoma
• 🫀 Bladder carcinoma
• 🧩 Multiple myeloma

📂 Types of Bone Metastases

• 🔴 Osteolytic (bone destruction – e.g. myeloma, renal, breast, lung, melanoma)
  • ↑ Calcium, normal ALP (unless fracture)
  • Best seen on plain X-ray
  • Progress faster than blastic lesions
• ⚪ Osteoblastic (sclerotic) (bone formation – e.g. prostate, some breast/lung)
  • ↑ ALP, calcium may be high or normal
  • Best seen on bone scans
• 🔀 Mixed lesions: most common overall; reflect activity of both osteoclasts and osteoblasts

🩺 Clinical Features

• 🦴 Bone pain (often worse at night)
• ⚡ Pathological fractures, deformity
• 🧍 Reduced mobility, impaired function

🔍 Differentials

• Osteoarthritis, degenerative disease
• Paget’s disease
• Osteoporosis
• Disc disease

🔎 Investigations

• 🧪 Bloods: ↑ Calcium, ↑ ALP (esp. blastic lesions)
• 🦴 X-rays: detect lytic lesions
• ☢️ Bone scan (Tc-99m): best for sclerotic disease, but can miss purely lytic lesions
• 🖥️ CT/MRI: for local staging, spinal involvement
• 📋 Skeletal survey: especially in myeloma
• 🔬 Orthopaedic review for impending fractures

⚠️ Complications

• Severe pain, immobility
• Pathological fractures
• Spinal cord compression → neurological deficits
• Cranial nerve palsies, nerve root compression
• Hypercalcaemia (confusion, arrhythmias)
• Bone marrow suppression (anaemia, cytopenias)

🛡️ Prevention

• In breast, prostate & myeloma → bisphosphonates delay first skeletal events
• Bisphosphonates may also prolong survival in metastatic breast cancer

💊 Management (depends on primary cancer)

• 💊 Analgesia: WHO pain ladder, opioids for severe pain
• 🦴 Orthopaedics: surgical stabilisation, decompression for fractures or cord compression
• ☢️ Radiotherapy: pain relief, local control, spinal cord compression
• 🎯 Systemic anti-cancer therapy: endocrine (e.g. prostate/breast), chemo, targeted therapy, radionuclides (e.g. samarium, radium-223)
• 🧪 Bone-modifying agents: – Bisphosphonates (e.g. Zoledronic acid 4 mg IV) → ↓ bone resorption, ↓ pain, ↓ hypercalcaemia – Denosumab (anti-RANKL antibody) → effective alternative, esp. in renal impairment
• 🏃 Physical activity encouraged, but balance against fracture risk → supervised programmes

📌 Exam Pearl: – Osteolytic → think myeloma, renal, breast. – Osteoblastic → think prostate. – Mixed → most others. – Always consider spinal cord compression in a cancer patient with new back pain.

📚 References

• NICE: Metastatic Spinal Cord Compression
• Cancer Research UK – Secondary Bone Cancer