Four years of clinical experience with Radium-223 for the treatment of castration-resistant prostate cancer

Radium-223 is an alpha-emitting radiopharmaceutical that significantly prolongs overall survival in patients with castration-resistant prostate cancer and symptomatic bone metastases. We report a retrospective analysis of our clinical experience with Radium-223 in the first 68 patients treated.

The incidence of hematologic, gastrointestinal, and other adverse events was identified, including events that led to treatment discontinuation or delay. Alterations in bone pain and prostate-specific antigen and serum alkaline phosphatase levels were evaluated. Bone scan changes were identified and correlated with the clinical course.

Sixty-eight patients were included in the study. The median number of radium-223 injections was 5 (range 1-6), with 69% of patients receiving 5 to 6 injections. The most common side effects were digestive alterations in 24 patients, anemia in 7 patients, and thrombocytopenia in 5 patients. Clear downward trends in serum alkaline phosphatase were seen, that were less clear in prostate-specific antigen. Mean serum alkaline phosphatase decreased from baseline in 77% of the patients, and prostate-specific antigen in less than 40%. The majority of patients (62) experienced an improvement in bone pain intensity or no increase in bone pain intensity. No prostate-specific antigen flare phenomenon was noted.

Radium-223 was generally well tolerated and there were no safety concerns. The adverse events were mild and manageable. A decline in serum alkaline phosphatase was more common than a decline in prostate-specific antigen. Monitoring changes in serum alkaline phosphatase dynamics may be useful.