Effects of low-dose cisplatin on ⁸⁹Sr therapy for painful bone metastases from prostate cancer: A randomized clinical trial

This study evaluated the effects of low-dose cisplatin plus ⁸⁹Sr versus ⁸⁹Sr alone in the treatment of painful bone metastases from prostate cancer, addressing both pain palliation and cytostatic effects. Methods: Seventy patients with metastatic hormone-refractory prostate cancer were randomized into 2 groups: One group (arm A) received 148 MBq ⁸⁹Sr plus 50 mg/m² cisplatin, and the other group (arm B) received 148 MBq ⁸⁹Sr plus placebo. After treatment, the patients were followed up until death to evaluate the outcome variables: grade and duration of pain palliation, onset of new painful sites, changes in bone disease, global survival, serum prostate-specific antigen and alkaline phosphatase changes, and hematologic toxicity. Results: Overall pain relief occurred in 91% of patients in arm A and 63% of patients in arm B (P <0.01), with a median duration of 120 d in arm A and 60 d in arm B (P = 0.002). New painful sites on previously asymptomatic bone metastases appeared in 14% of patients in arm A and in 30% of patients in arm B (P = 0.18). The median survival without new painful sites was 4 mo in arm A and 2 mo in arm B (P = 0.04). Bone disease progression was observed in 27% of patients in arm A and in 64% of patients in arm B (P = 0.01). Median global survival after therapy was 9 mo in arm A and 6 mo in arm B (P = 0.30). Transient and moderate hematologic toxicity, as determined by World Health Organization criteria, was apparent in both arms without significant differences. Conclusion: The addition of a low dose of cisplatin enhances the effect of a standard dose of ⁸⁹Sr without significant side effects, producing a significant improvement in pain palliation and a cytostatic effect on bone disease.