Adjuvant clodronate treatment does not reduce the frequency of skeletal metastases in node-positive breast cancer patients: 5-year results of a randomized controlled trial.

Purpose: Bisphosphonates have effectively reduced the development and progression of bone metastases in advanced breast cancer. The aim of this study was to determine whether bone metastases could be prevented by adjuvant clodronate treatment in patients with primary breast cancer.

Patients And Methods: Between 1990 and 1993, 299 women with primary node-positive breast cancer were randomized to clodronate (n = 149) or control groups (n = 150). Clodronate 1,600 mg daily was given orally for 3 years. All patients received adjuvant therapy: premenopausal six cycles of CMF chemotherapy and postmenopausal antiestrogens (randomized to tamoxifen 20 mg or toremifene 60 mg/d for 3 years). Seventeen patients were excluded from the analyses because of major protocol violations. The final population was 282 patients. Intent-to-treat analyses were also performed for all major end points. The follow-up time was 5 years for all patients.

Results: Bone metastases were detected equally often in the clodronate and control groups: 29 patients (21%) versus 24 patients (17%) (P: = .27). The development of nonskeletal recurrence was significantly higher in the clodronate group compared with controls: 60 patients (43%) versus 36 patients (25%) (P: = .0007). The overall survival (OS) and disease-free survival (DFS) rates were also significantly lower in the clodronate group than in the controls (OS, 70% v 83%, P: = .009; DFS, 56% v 71%, P: = .007, respectively). In multivariate analyses, clodronate remained significantly associated with DFS (P: = .009).

Conclusion: Adjuvant clodronate treatment does not prevent the development of bone metastases in node-positive breast cancer patients. However, clodronate seems to have a negative effect on DFS by increasing the development of nonskeletal metastases.