Bisphosphonate treatment in primary breast cancer: results from a randomised comparison of oral pamidronate versus no pamidronate in patients with primary breast cancer.

Purpose and Patients: During the period from January 1990 to January 1996 a total of 953 patients with lymph node negative primary breast cancer were randomised to oral pamidronate (n=460) 150 mg twice daily for 4 years or no adjuvant pamidronate (n=493) in order to investigate whether oral pamidronate can prevent the occurrence of bone metastases and fractures. The patients received adjuvant chemotherapy, loco-regional radiation therapy, but no endocrine treatment.
Results: During the follow-up period the number of patients with pure bone metastases was 35 in the control group and 31 in the pamidronate group. The number of patients with a combination of bone and other distant metastases were 22 in the control group and 20 in the pamidronate group. The hazard rate ratio for recurrence in bone in the pamidronate group compared to the control group was 1.03 (95% confidence interval 0.75-1.40) and p=0.86. No effect was observed on overall survival. In a small subgroup of 27 patients from the study, 12 of whom were treated with pamidronate a significant bone preserving effect was observed on bone mineral density in the lumbar spine, but not in the proximal femur.
Conclusion: The results from the trial do not support a beneficial effect of oral pamidronate on the occurrence of bone metastases or fractures in patients with primary breast cancer receiving adjuvant chemotherapy.