Interventional radiology for treatment of bone metastases

Therapeutic advances in oncology have led to longer survival in many forms of cancer, including those complicated by bone metastases. When a bone metastasis is painful or when there is a risk of fracture, interventional radiology procedures can be carried out for pain control and/or stabilisation. All of these techniques can be performed under local anaesthesia. Cementoplasty and vertebroplasty are stabilisation procedures consisting in the percutaneous injection of acrylic cement into a lytic bone lesion. The effect on pain can be explained by the consolidation of weakened, fractured or pre-fractured bone, but also to a lesser extent by the toxic, chemical and thermal effect of the cement. Tumour ablation techniques include alcoholisation or thermal ablation (by heat with radiofrequency and microwave or cold by cryoablation). Percutaneous thermal ablation of bone tumours is most often performed as a palliative measure resulting in a significant and lasting reduction in symptoms. Radiofrequency ablation consists in placing needles through which an electrical current passes. Microwave ablation acts by causing very high frequency vibrations of water molecules. Cryoablation releases argon gas at the tip of the needle, forming an "ice ball" effectively destroying tumour cells. Any of these techniques can be combined to radiation therapy, performed before or after radiation. Finally, tumour embolisation can have a goal of pain control, or preparation of surgery to reduce the risk of peroperative haemorrhage.