SEYI IDOWU MCh MD FMCEM FWACS FMCOrtho

Learning Points

– Epidemiology

– Clinical Presentation

– Investigations

– Treatment

– Follow‑up

– Prognosis

Epidemiology

– Bone is the 3rd most common site for metastasis (after lung and liver).

– Solitary bone lesions in adults >40 are 500× more likely metastatic than primary.

– Common in age >50.

– Most common sites: spine > pelvis > proximal femur > humerus.

– Pathologic fractures: proximal femur then proximal humerus; 65% non‑union rate.

– Femoral neck 50%, pertrochanteric 20%, subtrochanteric 30%.

– Acral lesions rare; usually from lung carcinoma.

– Lung is most common source of occult mets.

– Common primaries: Breast (female), Prostate (male), Lung, Thyroid, Kidney.

– Mnemonic: BLT and a Kosher Pickle.

Etiology

– Mechanism: intravasation → migration → immune evasion → homing via CXCL12 → extravasation → angiogenesis.

– Lytic lesions: tumor secretes PTHrP → RANKL activation → osteoclast activation → bone destruction.

– Osteoblastic lesions: prostate/breast tumors secrete ET‑1 → WNT activation → osteoblast stimulation.

Pathogenesis

– Vascular spread via Batson’s valveless venous plexus.

– Arterial spread → distal extremity metastases, especially from lung/renal primaries.

Clinical Presentation

– Night pain, weight loss, pain on weight‑bearing, enlarging mass.

– 8–30% present with pathologic fracture; 90% require surgery; healing potential poor.

– Hypercalcemia: confusion, weakness, polyuria, vomiting, dehydration.

– Neurologic deficits from spinal cord compression.

Investigations

– Baseline labs: FBC, CRP, ESR, U/E, serum calcium.

– Plain radiographs.

– MRI.

– Localized CT + Chest/Abdominal CT.

– Technetium‑99 bone scan.

– Biomarkers and genetic studies.

– Biopsy.

Non‑Operative Treatment

– Asymptomatic lesions or nondisplaced fractures in non‑weight‑bearing bones.

– Bisphosphonates for lytic/blastic/mixed lesions.

– Denosumab: superior to zoledronic acid.

– Radiotherapy: pain palliation in 70%; complete relief in 30%.

– Chemotherapy, immunotherapy, hormone therapy.

Operative Treatment

– Fixation must not rely on bone healing → use endoprosthesis for proximal femur.

– Life expectancy >6 months predicts healing.

– Indications: failed non‑operative treatment, severe pain.

– Wide resection lowers recurrence vs curettage.

Operative Adjuncts

– Post‑op radiotherapy unless contraindicated.

– Begin radiotherapy 2–3 weeks post‑op.

– Indications for prophylactic fixation: >50% cortical destruction, subtrochanteric permeative lesions, >50–75% metaphyseal loss, persistent pain.

Options for Long Bone Mets

– Intramedullary fixation.

– Plate fixation with cementation.

– Primary joint replacement.

– Endoprosthetic replacement.

Additional Treatment Options

– Pre‑operative embolization (renal/thyroid primaries).

– Radiofrequency ablation.

– Cementoplasty.

– Cryoablation.

– High‑intensity focused ultrasound.

Prognosis

– Median survival: Thyroid 48 mo, Prostate 40 mo, Breast 24 mo, Kidney 6 mo–5 yr, Lung 6–7 mo.

Spinal Metastases

– 5–30% of cancer patients develop spinal mets.

– 70% thoracic, 20% lumbar, 10% cervical.

– 94–98% involve vertebra or epidural space.

– Spread: arterial, Batson plexus, direct invasion.

Primary Sources of Spinal Mets

– Lung 31%, Breast 24%, GI 9%, Prostate 8%, Lymphoma 6%, Melanoma 4%, Unknown 2%, Kidney 1%, Myeloma/others 13%.

Tokuhashi Score

– Evaluates prognosis using 6 elements: general condition, extraspinal mets, vertebral involvement, visceral mets, primary tumor, neurologic deficit.

– 0–8: <6 months; 9–12: >6 months; 12–15: >1 year.

Management Considerations

– Pain, neurologic deficit, instability, number of mets, tumor sensitivity, patient prognosis.

Non‑Operative (Spine)

– Pain control and bracing.

– Indicated for stable fractures, no neurologic deficit, life expectancy <6 months, SINS <7.

Medical Management

– Cytotoxic chemotherapy, hormonal therapy, dexamethasone, opioids, NSAIDs, antiepileptics, bisphosphonates.

Radiotherapy

– Mainstay of treatment: 80% pain relief; 48% neurologic response.

– Common regimen: 30 Gy in 10 fractions.

Spine Surgery Options

– Radical spondylectomy with anterior/posterior stabilization.

– Kyphoplasty/vertebroplasty for stable fractures without compression.

– Pre‑op embolization for renal/thyroid mets.

– 95% local control with surgery + radiation.

Follow‑up

– Every 3 months for 2 years.

– Every 6 months for next 3 years.

– Yearly for 5 years.

Summary

– Bone metastasis increasing due to rising cancer survival.

– Requires MDT.

– Biopsy when primary carcinoma unknown.

– Goals: pain control, maintain independence, prevent fractures.