Metastatic bone disease
🦴 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
