Radium-223: Long-Term Safety Confirmed in Prostate Cancer
Seven-year follow-up data on over 1400 patients show radium-223's long-term safety, with a low 2% secondary malignancy rate, reflecting real-world use.
In an interview with Targeted OncologyTM, Fred Saad, MD, professor and chairman of Urology and director of Genitourinary Oncology at the University of Montreal Hospital Center, discusses 7-year follow-up of the largest prospective global study of radium-223 (Xofigo) therapy for prostate cancer.
One of the primary questions surrounding radium-223, an infused form of radiation therapy, has been its long-term safety, according to Saad. Specifically, there has been concern about the potential development of secondary malignancies years after treatment. This apprehension stems from historical experiences, such as the prophylactic radiation therapy for stage I seminoma in testicular cancer, which, after 2 decades, was found to induce secondary cancers in younger patients. Therefore, investigating the long-term safety of radium-223 was an imperative.
This study provides the longest-term follow-up data to date for radium-223, encompassing over 1400 patients with a 7-year follow-up period. The patient cohort largely reflects real-world demographics, with a median age of 73, which is older than typically seen in clinical trials. Approximately 80% of patients presented with bone-only disease, while nearly 20% had extramedullary disease, including small lymph node involvement, offering valuable insights into outcomes in a broader patient population.
An encouraging finding was that 67% of patients received 5 or more cycles of radium-223. This suggests improved understanding and management of the therapy, emphasizing the importance of not delaying treatment until patients are overly symptomatic, which can limit the number of cycles received, notes Saad. Optimal benefits from radium-223, including long-term survival improvements, are cumulatively achieved with a greater number of cycles, ideally 5 or 6.
"That was reassuring, that in the real world we're seeing about 70% of patients getting 5 or 6 cycles," Saad said in the interview.
Regarding the critical concern of secondary malignancies, the study reported a rate of only 2%. For this older patient population, this low incidence is positive, indicating that radium-223 does not appear to significantly increase the risk of secondary malignancies beyond what would be expected over time in this age group.
