Retrospective evaluation of the safety of pamidronate administration at the dose of 90 mg/day/month in Japanese breast cancer patients with bone metastasis

The Japanese Ministry of Health, Labor and Welfare approved the use of pamidronate in November 2004 at a dose of 90 mg/day/month especially for Japanese breast cancer patients with lytic bone metastasis. But no safety data have been shown for these Japanese patients thus far. Therefore, we evaluated the safety of pamidronate treatment for breast cancer patients with bone metastasis at the dose of 90 mg/day/month since July 1, 2004 until Dec 31, 2004, retrospectively, in our institute, the Shikoku Cancer Center. No definite severe side effects were detected in these patients, including renal dysfunction and thrombocytopenia. In addition, there were no definite alternations in hemoglobin titers, platelet counts, BUN, serum creatinine and potassium levels in one month and 3 months after beginning the treatment except for significant alternations in RBC counts in one month and in the serum calcium level 3 months later (p=0.03). Improvements of clinical symptoms or data due to bone metastases, i.e., bone pain or elevation of tumor markers, were obtained in 91% of patients. As a conclusion, pamidronate administration at the dose of 90 mg/day/month was safe for Japanese breast cancer patients with bone metastasis.