Teletherapy and radiopharmaceutical therapy of painful bone metastases

Bone pain from metastatic disease is most common in cancers of the breast, prostate, and lung. Despite the World Health organization algorithm for treating such pain, the outcomes are not often satisfactory. In 2005, there will be 3 radiopharmaceuticals available in the United States that can reduce or relieve bone pain caused by osteoblastic metastases with apparently equal efficacy. Phosphorus-32 as sodium phosphate, strontium-89 (⁸⁹Sr) as the chloride, and samarium-153 lexidronam may all be given intravenously (and ³²P also orally) in patients where bone scintigraphy demonstrates a metastatic lesion causing the patient’s bone pain. Side effects are usually mild and include pancytopenia with leukocyte and platelet nadirs at approximately 50% of baseline, and a mild-to-moderate, but brief, increase in pain (“flare”) in approximately 10% of patients. At least 1 of these radiotracers, ⁸⁹Sr, has the availability to reduce the incidence of new bone metastases as well, but, given alone, none prolong life. In a few studies in which ⁸⁹Sr has been combined with chemotherapy, prolongation of patient survival has been demonstrated. Many questions remain as to the optimization of use of this group of radiopharmaceuticals, including whether combinations of radiopharmaceuticals with each other, with bisphosphonates or with chemotherapy can improve the therapeutic outcomes even more.