Oral adjuvant clodronate therapy could improve overall survival in early breast cancer: results from an updated systematic review and meta-analysis

Bisphosphonates and breast cancer survival: a meta-analysis and trial sequential analysis of 81508 participants from 23 prospective epidemiological studies

BACKGROUND

We assessed the effect of bisphosphonates (BPs) on breast cancer (BCa) patient survival and explored how long the effect can persist after treatment.

METHODS

We performed a meta-analysis and trial sequential analysis (TSA) of prospective studies including randomized controlled trials (RCTs) and cohort studies. We performed extensive sensitivity analyses to assess the robustness of the findings.

RESULTS

Seventeen RCTs and eight cohorts with 81508 BCa patients were identified. A significant beneficial effect of BPs on BCa survival was found (RR, 0.725; 95% CI, 0.627-0.839), and the TSA results also suggested firm evidence for this beneficial effect. Both summarized results from RCTs and cohorts provided firm evidence for this effect, although the effect estimates were stronger from cohorts than RCTs (RR, 0.892; 95% CI, 0.829-0.961; 0.570; 95% CI, 0.436-0.745; respectively). This beneficial effect was confirmed for bone-metastases (RR, 0.713; 95% CI, 0.602-0.843) and postmenopausal women (RR, 0.737; 95% CI, 0.640-0.850). Importantly, our results demonstrated that this beneficial effect was retained at least 1-2 years after treatment completion (RR, 0.780; 95% CI, 0.638-0.954) and could persist for up to more than 4 years after treatment completion (RR, 0.906; 95% CI, 0.832-0.987). Extensive sensitivity analyses showed the robustness of our results. The GRADE quality of evidence was generally judged to be moderate to high.

CONCLUSIONS

The present study provides firm evidence for a significant beneficial effect of BPs on BCa survival in patients with early-stage BCa, and this effect was retained at least 1-2 years after BP treatment completion.

Diagnostic PET Imaging of Mammary Microcalcifications Using 64Cu-DOTA-Alendronate in a Rat Model of Breast Cancer

The development of improved breast cancer screening methods is hindered by a lack of cancer-specific imaging agents and effective small-animal models to test them. The purpose of this study was to evaluate ⁶⁴Cu-DOTA-alendronate as a mammary microcalcification-targeting PET imaging agent, using an ideal rat model. Our long-term goal is to develop ⁶⁴Cu-DOTA-alendronate for the detection and noninvasive differentiation of malignant versus benign breast tumors with PET. Methods: DOTA-alendronate was synthesized, radiolabeled with ⁶⁴Cu, and administered to normal or tumor-bearing aged, female, retired breeder Sprague-Dawley rats for PET imaging. Mammary tissues were subsequently labeled and imaged with light, confocal, and electron microscopy to verify microcalcification targeting specificity of DOTA-alendronate and elucidate the histologic and ultrastructural characteristics of the microcalcifications in different mammary tumor types. Tumor uptake, biodistribution, and dosimetry studies were performed to evaluate the efficacy and safety of ⁶⁴Cu-DOTA-alendronate. Results:⁶⁴Cu-DOTA-alendronate was radiolabeled with a 98% yield. PET imaging using aged, female, retired breeder rats showed specific binding of ⁶⁴Cu-DOTA-alendronate in mammary glands and mammary tumors. The highest uptake of ⁶⁴Cu-DOTA-alendronate was in malignant tumors and the lowest uptake in benign tumors and normal mammary tissue. Confocal analysis with carboxyfluorescein-alendronate confirmed the microcalcification binding specificity of alendronate derivatives. Biodistribution studies revealed tissue alendronate concentrations peaking within the first hour, then decreasing over the next 48 h. Our dosimetric analysis demonstrated a ⁶⁴Cu effective dose within the acceptable range for clinical PET imaging agents and the potential for translation into human patients. Conclusion:⁶⁴Cu-DOTA-alendronate is a promising PET imaging agent for the sensitive and specific detection of mammary tumors as well as the differentiation of malignant versus benign tumors based on absolute labeling uptake.

Bisphosphonate and risk of cancer recurrence: protocol for a systematic review, meta-analysis and trial sequential analysis of randomised controlled trials

INTRODUCTION

No consensus exists on the associations between adjuvant treatment with bisphosphonates and cancer recurrence risk among patients with primary early-stage cancers. We plan to perform a comprehensive systematic review, study-level meta-analysis and trial sequential analysis of randomised controlled trials to comprehensively summarise evidence of the bisphosphonate treatment for difference cancers.

METHODS AND ANALYSES

We will report our results according to the PRISMA guideline. The primary outcomes include any cancer recurrence and bone metastasis and secondary outcomes include events of local recurrence, regional recurrence or non-skeletal distant metastasis, disease-free survival and overall survival. We will perform systematic electronic searches and other manual searches. To be conservative, all statistical analyses will be conducted with random-effects models. Cumulative meta-analyses and trial sequential analyses will be performed to assess whether and when firm evidence is reached. Various sensitivity analyses and rigid publication bias analyses will be performed to challenge the consistency and robustness of results. We will also grade the quality of evidence with the GRADE system.

ETHICS AND DISSEMINATION

Ethical approval is not required in this study. The findings will be submitted for publication in a peer-reviewed journal and also presented at relevant national and international conferences.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42014014699.

Clodronate inhibits tumor angiogenesis in mouse models of ovarian cancer

PURPOSE

Bisphosphonates have been shown to inhibit and deplete macrophages. The effects of bisphosphonates on other cell types in the tumor microenvironment have been insufficiently studied. Here, we sought to determine the effects of bisphosphonates on ovarian cancer angiogenesis and growth via their effect on the microenvironment, including macrophage, endothelial and tumor cell populations.

EXPERIMENTAL DESIGN

Using in vitro and in vivo models, we examined the effects of clodronate on angiogenesis and macrophage density, and the overall effect of clodronate on tumor size and metastasis.

RESULTS

Clodronate inhibited the secretion of pro-angiogenic cytokines by endothelial cells and macrophages, and decreased endothelial migration and capillary tube formation. In treated mice, clodronate significantly decreased tumor size, number of tumor nodules, number of tumor-associated macrophages and tumor capillary density.

CONCLUSIONS

Clodronate is a potent inhibitor of tumor angiogenesis. These results highlight clodronate as a potential therapeutic for cancer.

Adjuvant zoledronic acid therapy for patients with early stage breast cancer: an updated systematic review and meta-analysis

BACKGROUND

Zoledronic acid is a potent inhibitor of osteoclast-mediated bone resorption and has been widely used in bone metastasis malignancies and postmenopausal osteoporosis as a preventive therapy against skeletal-related events. The purpose of this study was to evaluate the clinical outcome of zoledronic acid as an adjuvant therapy for patients with early stage breast cancer.

PATIENTS AND METHODS

Entries in the PubMed and EMBASE databases up to 12 July 2013 were systematically reviewed. Online abstracts from the proceedings of the Annual Meetings of the American Society of Clinical Oncology (ASCO) (1992-2013) and the San Antonio Breast Cancer Symposium (SABCS) (2004-2013) were also reviewed. Primary endpoints included overall survival (OS) and disease-free survival (DFS), while secondary endpoints included bone metastasis-free survival (BMFS), distant metastasis-free survival (DMFS), and fracture-free rate (FFR).

RESULTS

A total of eight studies including 3,866 subjects and 3,864 controls met our search criteria and were evaluated. The use of zoledronic acid was found to improve OS (relative risk (RR), 0.88; 95% confidence interval (CI), 0.77-1.01; p-value = 0.06) and DMFS (RR, 0.77; 95% CI, 0.60-1.00; p-value = 0.05). Furthermore, statistically significant benefits were associated with BMFS (RR, 0.81; 95% CI, 0.66-0.99; p-value = 0.04) and FFRs (RR, 0.75; 95% CI, 0.61-0.92; p-value = 0.007). In contrast, there was no significant difference in DFS with the application of zoledronic acid (RR, 0.88; 95% CI, 0.72-1.09; p-value = 0.24). Sensitivity analysis further identified the improvement of 5-year OS for the adjuvant zoledronic acid therapy in early stage breast cancer patients (RR, 0.86; 95% CI, 0.75-0.99; p-value = 0.03), while a borderline statistically significant benefit was observed for 5-year DFS (RR, 0.90; 95% CI, 0.81-1.00; p-value = 0.06).

CONCLUSION

Zoledronic acid as an adjuvant therapy appears to improve the 5-year OS rate for early stage breast cancer patients, and was associated with a protective effect for the bone metastases and fractures evaluated in more than 7,000 patients. However, further research is needed to confirm our findings, and sub-group analyses according to menopause status or hormone status may provide further insight.

Adjuvant Therapy With Zoledronic Acid and Menopausal Status

Zoledronic acid as adjuvant therapy in breast cancer patients has been shown to have a beneficial effect on OS. Adjuvant treatment with clodronate also may improve OS in patients with early breast cancer. Further study with analysis of subgroups by age or menopausal status should be performed to investigate adjuvant therapy with bisphosphonates in breast cancer patients.