Bisphosphonates and radiation therapy for palliation of metastatic bone disease

Radiotherapy is an established treatment for metastatic bone pain. It may be delivered as a localised low dose treatment for localised bone pain or systemically for more widespread symptoms using hemibody external beam radiotherapy or intravenous bone-seeking radioisotopes. Bisphosphonates have been shown to reduce morbidity from bone metastases when given to patients with asymptomatic disease from myeloma and primary breast and prostate cancers. They also reduce metastatic bone pain in these sites. In the absence of randomised data comparing radiotherapy with bisphosphonates in the same clinical setting, comparison of the response rates from individual trials of the two modalities suggests that the overall pain response in all tumour types from radiotherapy is around 80% compared to a similar rate in myeloma with bisphosphonates but only 40% in solid tumours. Optimal use of the two modalities requires further investigation but since they have different dose limiting toxicities their incorporation in a combined modality approach to metastatic bone pain is rational using the concepts of additive effect and spatial co-operation in which bisphosphonates provide background control alongside acute pain relief using radiotherapy. They are also an important alternative for bone pain where radiation tolerance has been reached or radiotherapy is not readily available.