Pamidronate as adjuvant treatment for prevention of bone metastasis in breast cancer

Abstract

888 Background: Bone is the most common site of distant recurrence in breast cancer. The primary mechanism of metastatic bone disease is stimulation of osteoclastic bone resorption by factors produced by the cancer cells. Bisphosphonates are potent inhibitors of osteoclastic bone resorption with proven efficacy in reducing tumor-associated skeletal complications. Several studies have investigated the adjuvant, or preventive, use of these drugs in breast cancer. Laboratory experiments have shown that the development of bone metastases can be inhibited by Bisphosphonates. Pamidronate is an easy to use potent inhibitor of osteolysis, given in conjunction with standard anticancer therapies. We evaluated the efficacy of adjuvant pamidronate therapy for prevention of bone metastasis in women with breast cancer. Methods: We analyzed the data of 429 patients with primary operable stage I-III breast cancer that were treated at KNUH during the period January 1999-December 2002. All patients had radical local therapy and systemic therapy performed according to our guidelines at that time. 258 patients were received adjuvant pamidronate therapy(parmidronate 15mg iv every 4 weeks and oral parmidronate 100mg daily during adjuvant chemotherapy). 171 patients had no bisphosphonate therapy. The patients were perimenopausal women. The mean age of patients was 53 years and the median follow-up period was 3.5 years. The clinicopathological characteristics of the patients were well balanced. Results: The incidence of bone metastasis was 2.3% in the parmidronate group and 8.7% in control group. The incidence of other sites metastasis in pamidronate group was lower than control group but no statistically significant. Overall survival and disease-free survival rate were equal in the both groups. Bone metastasis free survival was significantly higher in the pamidronate group compared to the control group. Conclusions: In the parmidronate group, the incidence of bone metastases was significantly reduced and bone metastasis free survival was significantly higher. We conclude that adjuvant parmidronate therapy significantly reduced the development of bone metastases in perimenopausal women with primary breast cancer. No significant financial relationships to disclose.