A randomised phase II study of oral pamidronate for the treatment of bone metastases from breast cancer.

47 patients with progressive, painful, predominantly lytic bone metastases from breast cancer were included in a randomised double-blind phase II trial comparing the effects of pamidronate 150 and 300 mg daily. Oral pamidronate produced either sclerosis or stabilisation of lytic metastases for at least 24 weeks in 5 of 24 and 3 of 23 patients at the 300 and 150 mg dose levels, respectively. Evidence of symptomatic improvement was observed in 5 of 22 (23%) and 7 of 22 (32%) patients for symptomatic disease at the respective doses. These improvements were accompanied by a reduction in the rate of bone resorption as shown by suppression (P = < 0.01) of urinary calcium and a non-significant fall in deoxypyridinoline. No obvious differences in efficacy were observed between the two dose levels. Gastrointestinal adverse events, principally comprising nausea and vomiting, were the most commonly reported side-effects leading to discontinuation of trial treatment in 4 of 24 and 2 of 23 patients at 300 and 150 mg dose levels, respectively. The poor tolerability of oral pamidronate coupled with the modest clinical effects reported here suggest that oral pamidronate will not replace the current strategy of regular intravenous infusions of pamidronate for the treatment of osteolytic bone disease.