Bone-Seeking Radiopharmaceuticals for Treatment of Osseous Metastases, Part 1: α Therapy with 223Ra-Dichloride

Metastatic disease to bone is commonly seen in the advanced stages of many cancers. The cardinal symptom, pain, is often the cause of significant morbidity and reduced quality of life. Treatment of bone pain includes nonsteroidal analgesics and opiates; however, long-term use of these drugs is commonly associated with significant side effects, and tolerance is common. External-beam radiation therapy is effective mainly in localized disease sites. Bone-targeting radiopharmaceuticals are beneficial in the management of patients with multiple metastatic lesions. This article focuses on the 3 most commonly used agents: the Food and Drug Administration-approved Sr-89-chloride, Sm-153-ethylenediaminete-tramethylene phosphonic acid (EDTMP), and Ra-223-dichloride. We will discuss the physical characteristics, clinical data, dosage, and administration of these agents, including optimal patient selection and toxicity associated with their use. These radioactive agents have proven efficacy in the treatment of painful osseous metastases from prostate cancer and breast cancer. Significant recent advances include use of these agents in combination with chemotherapy and the use of the alpha emitter Ra-223-dichloride in prostate cancer, primarily to improve survival and skeletal related events. The review is presented in 2 parts. The first will discuss the characteristics and clinical use of Ra-223-dichloride, and the second will discuss the beta emitters Sr-89 and Sm-153-EDTMP.