Evaluation of toxicity and efficacy of Re-186-hydroxyethylidene diphosphonate in patients with painful bone metastases of prostate or breast cancer

Twenty-eight patients (12 men with prostate cancer, 16 women with breast ca ncer) were included in a phase II trial to evaluate the efficacy of Re-186- hydroxyethylidene diphosphonate (HEDP) on pain from bone metastasis and the toxicity of this agent. Methods: After intravenous administration of 1295 MBq Re-186-HEDP, the efficacy was evaluated by means of a daily log. Result s: We observed an objective response in 67% of prostate cancer patients and in 36% of breast cancer patients. The mean duration of response was 45 d f or prostate cancer patients and 24 d for breast cancer patients. No major a dverse effects were observed. Marrow toxicity did not exceed grade 2 for wh ite blood cells and grade 3 for platelets using National Cancer Institute c riteria. Conclusion: Re-186-HEDP provides safe symptomatic relief of pain i n prostate cancer patients. The benefit of this treatment is less clear in breast cancer patients. Further studies should be conducted to evaluate tre atment by 186Re-HEDP at., earlier stage of the disease.