Introduction: Theoretically, the bisphosphonates used to treat metastatic bone disease could influence the results of nuclear bone scans which use the structurally similar technetium 99m methylene diphosphonate (99mTc MDP). A prospective clinical study was designed to explore this hypothesis.
Patients and methods: Patients with metastatic breast cancer receiving intravenous bisphosphonate (IVBP) therapy who had > or =3 osseous lesions on nuclear bone scan were eligible. A baseline bone scan (number 1) was performed as clinically indicated and IVBP with zoledronic acid was administered within 72 hours. A second bone scan (number 2) was performed within 72 hours of zoledronic acid dosing. Both bone scans were reviewed in a blinded fashion and assessed for changes in the number and intensity of osseous lesions. Ten patients were planned to yield at least 30 lesions.
Results: Ten patients were enrolled. One patient withdrew consent and 1 was excluded due to protocol deviation. Among the 8 patients were 163 assessable osseous lesions. The median time from bone scan number 1 to IVBP was 1 day (range, 1-2 days). The median time from IVBP to bone scan number 2 was 2 days (range, 1-3 days). The paired imaging showed no changes in the total number of bone metastases. One hundred sixty-one lesions were identical in both scans; in 1 patient there were 2 lesions that were discordant, one more intense, the other less intense.
Conclusion: These data do not support the hypothesis that IVBP therapy interferes with bone scan results.