Metastatic bone tumours
Metastatic cancer is much more common than primary bone cancer.
Two thirds of bone secondaries arise from adenocarcinomas of the breast or prostate. The remainder arise from carcinoma of the bronchus, adenocarcinoma of the kidney and thyroid.Metastases usually appear in the marrow cavity, damaging bone both directly through expansion and indirectly through bone reabsorption.
Patients may present with bone pain or a pathological fracture. Bone metastases may be the first sign of the primary tumour. There may be a leucoerythroblastic anaemia due to marrow replacement, hypercalcaemia and nerve or spinal cord compression.
The X-ray typically demonstrates a destructive lytic bone lesion, although some metastases appear sclerotic (e.g. prostate). Isotope bone scans are used to assess the extent of the lesions and to detect lesions that are not evident on X-ray.
Symptomatic treatments include analgesia, local radiotherapy and chemotherapy, internal fixation of any fractures and spinal decompression in vertebral collapse with spinal cord compression. Hypercalcaemia may require treatment.