Mestastatic Bone Tumours

Primary cancers which commonly metastasise to bone

  • In order of most-least common (but still not unusual):

Breast cancer

  • Bony metastases can be blastic (sclerotic) or lytic
  • Mean survival with bony metastases is around 24‐26 months

Prostate cancer

  • Produces sclerotic metastases
  • Because of the osteoblastic activity pathologic fractures are more likely to heal
  • Radiotherapy and hormone manipulation can reduce the fracture risk of a bone metastasis
  • Survival with prostatic bony metastases is around 45% at one year

Lung cancer

  • Usually gives rise to lytic bony metastases
  • Once bone metastases are present, mean survival is around 6 months

Renal cell carcinoma

  • Usually gives rise to potentially large and very vascular lytic 'blow out' bony metastases which can bleed tremendously with biopsy or surgery
  • With a single bone metastasis and a primary tumour amenable to resection (nephrectomy), surgery can potentially be curative
  • Mean survival with multiple bone metastases is 12‐18 months

Thyroid cancer

Clinical presentation

  • Bones most frequently involved with metastases include the vertebra, pelvis, ribs, skull and femurs
  • Pain may initially be misdiagnosed as a muscle strain however any pain with 'red flags' should be investigated at least with an xray initially
  • Patients may also present with pathological fracture

Investigations

  • X-ray
    • Can appear as lytic, sclerotic or mixed
    • If a lesion is found on xray, a primary bone tumour must be excluded by further imaging
    • Lesion not visible on x-ray until >50% of cortex destroyed - if clinical suspician high carry out further imaging
  • Other imaging - bone scan, occasionally MRI
  • If there are multiple metastases or the lesion is suspected to be metastatic, the primary tumour should be sought
  • Blood tests - serum calcium (for hypercalcaemia), LFTs (to look for liver mets), plasma protein electrophoresis (for myeloma), full blood count and U&E

Management

  • Surgery usually indicated regardless of prognosis as a paliative procedure
  • Skeletal stabilization or joint replacement may be required in some cases where there may be a risk of impending pathological fracture:
    • Lesions which are very painful (especially on weight bearing)
    • Lesions which occupy >50% of the diameter of the bone
    • Lesions with with cortical thinning