Palliative radiation with a radiolabeled diphosphonate (rhenium-186 etidronate) in patients with hormone-refractory disseminated prostate carcinoma

Material and methods: The present study investigates the safety and efficac y of 2590 MBq rhenium-186 ((186)Rc) etidronate (i.e. twice the activity nor mally used) administered intravenously in 15 patients with disseminated pro static carcinoma and bone pain. Results: Pain relief was observed in 11 of 14 evaluable patients (79%), 4 of whom became completely free from. pain. F ive of the responding patients also noted an improvement in daily activity and two found it possible to reduce or discontinue morphine medication. Pai n relief occurred within one week in four patients, and within two weeks in eight of the responding patients. The mean duration of pain relief after t he first course of Re-186-etidronate was 6 weeks (range 4-10). The toxicity was mild (less than or equal to grade 2), transient, and restricted to hem atological toxicity. Conclusions: Re-186-etidronate provided rapid pain-rel ief and had mild toxicity in most patients with disseminated hormone-refrac tory prostatic carcinoma, but doubling the activity did not markedly improv e the efficacy.