Differential effect of zoledronic acid on normal trabecular and cortical bone density in oncologic patients with bone metastases.

PURPOSE: To evaluate bone density changes at the level of normal bone and bone metastases after zoledronic acid (ZA) treatment in oncologic patients. MATERIALS AND METHODS: We retrospectively evaluated 72 consecutive adult patients with histologically confirmed solid tumors with at least 1 newly diagnosed bone metastatic lesion. Bone metastases were diagnosed by bone scans and confirmed with computed tomography (CT). Patients received intravenous ZA, 4 mg, by 15-min infusion every 28 day through a peripheral or a central venous access and were monitored for at least 3 months and a maximum of 24 months. Bone density was determined at the level of bone metastases and at the level of normal trabecular and cortical bone using a ROI-based approach. RESULTS: A significant increase was demonstrated at the level of normal trabecular bone of the calvarium and the femoral neck. No significant increase of density was observed at the level of the normal cortical bone. Bone metastases showed a significant increase in CT density as compared to baseline up to 24 months after zoledronic acid. CONCLUSION: We have found that long term treatment with ZA increases trabecular bone density in oncologic patients whereas normal cortical bone changes are not detectable.

A prospective analysis of CT density measurements of bone metastases after treatment with zoledronic acid.

OBJECTIVE: The objective was to prospectively determine CT density changes in bone metastases, before and after intravenous zoledronic acid for a maximum period of 12 months. PATIENTS AND METHODS: Twenty-three consecutive patients presented with bone metastases and underwent therapy with zoledronic acid from December 2004. All patients underwent CT of the chest, abdomen, and pelvis. Bone density, measured in Hounsfield units (HU), was determined by segmenting lesions in the same anatomical area of the metastasis sites on the axial images of the sequential series of CT examinations. The effects of zoledronic acid were evaluated by calculating absolute and relative increases in bone density. RESULTS: The patients presented with multiple metastases in 65% of the cases. When compared with the baseline, all groups demonstrated a significant increase in bone density, which significantly (p < 0.01) correlated with the number of zoledronic acid administrations. There was increased bone density of at least 100% in 57%, and an increase of at least 50% in 87% of the patients. This increase was significant in both lytic and sclerotic metastases after 3 months of therapy. No significant bone density difference was found in normal-appearing bone. CONCLUSION: Bone density measured by CT increases at metastatic sites after zoledronic acid treatment, regardless of the type of metastasis, in contrast to apparently normal bone.