Radionuclide therapy of bone metastases

Many tumors (like prostate- and breast cancer) induce osseous metastases that need to be treated. Bone targeted radionuclide therapy should be performed at an early stage in patients with painful bone metastases and scintigraphically positive lesions. The combination of external beam irradiation and systemic administration of radionuclides is often advantageous and can be performed without clinical problems. In patients with hormone-refractory prostate cancer and bone metastases, radionuclide therapy is increasingly performed as antitumor treatment for asymptomatic patients in clinical trials. By randomised, controlled clinical phase-II studies, it has been shown that new therapy regimens can prolong the progression-free interval and overall survival. New protocols that have been proposed represent the simultaneous application of chemotherapy and radionuclides. Side effects of such protocols are kept within a low toxicity level by reducing the dose of the chemotherapeutic agent (low-dose-chemotherapy). This combined therapy approach, however, is able to generate a radiosensitive state in the tumor cells resulting in an increased tumoricide efficiency of radionuclides. A different, innovative approach is the administration of multiple radionuclide injections at defined time intervals aiming at killing tumor cells with higher radiation doses. Side effects of these new treatment regimens can be scored as moderate. Consequently, in hormone-refractory prostate cancer patients, such new protocols should be considered as an alternative treatment option after standardised therapy regimens have been accomplished. In this situation, extensive experience for treating and selecting appropriate patients is crucial. A randomised pase-III study for the prove of an increased progression-free interval and overall-survival by radionuclide therapy is still missing. (orig.)