Strontium 89 in early relapse of hormone treated metastatic prostate cancer: can it delay onset of bone pain

Purpose/Objective: To determine whether early use of strontium 89 (Sr89) in patients with metastatic prostate cancer whose disease is progressing despite hormonal treatment will delay the onset of bone pain, usually the first clinical result of relapse. Materials/Methods: 167 men with hormone treated metastatic prostate cancer, in whom PSA was rising from post-treatment nadir, were randomised to receive Sr89, 150MBq, or a placebo injection. The study was double-blinded. The time to onset of pain requiring a change in treatment and to secondary endpoints-time to recommendation for radiotherapy, clinical relapse and death were also recorded. Results: The groups were well matched for demographic characteristics, clinical history and haematological parameters but the Solaway score bone scan assessment was higher for the Sr89 group. Treatment was well tolerated with toxicity confined to the expected haematological effects. In the placebo group the median time to the development of pain was 168 days with 18% pain free at one year. The onset of pain requiring treatment was significantly delayed by Sr89, (hazard ratio 0.606, 95% CI 0.414, 0.889, p=0.0103; median time to onset of pain of 213 days, with 33% free of pain at one year. Although there was no significant difference in time to recommendation for radiotherapy and clinical relapse there was a trend apparent in favour of Sr89, but not in time to death. Conclusions: It remains uncertain how to manage patients with hormone treated prostate cancer at the stage of relapse detected only by a rise in PSA. This study shows that a single injection of Sr89 may significantly increase the symptom free period before clinical bone pain occurs.