Effect of clodronate treatment on bone scintigraphy in metastatic breast cancer

Because of their high affinity for bone, bisphosphonates are used both in the treatment of benign and malignant bone disease and in radiopharmaceutical bone imaging. A prospective study was undertaken to evaluate whether intravenous clodronate (dichloromethylene bisphosphonate) therapy might affect the results of bone scintigraphy with 99mTc-labeled methylene diphosphonate (MDP). In 11 female patients with breast cancer and metastatic bone disease, quantitative bone scans were obtained using a region of interest (ROI) method on Days 0 and 22. After intravenous clodronate therapy from Day 1 to Day 21, all metastatic bone lesions were still detectable, and median ROI ratios did not differ to a statistically significant extent from baseline values. Serum calcium levels decreased (p = 0.0449), whereas parathyroid hormone concentrations showed an increase (p = 0.0053). Mean serum levels of creatinine, inorganic phosphorus, osteocalcin, gamma glutaminyl-transpeptidase and alkaline phosphatase remained unchanged. However, a more than twofold rise in the serum activity of alkaline phosphatase was measured in three patients. We conclude that 3 wk of intravenous clodronate treatment did not impair the sensitivity of 99mTc-MDP bone scintigraphy in detecting bone lesions in patients with metastatic breast cancer.