Abstract
BackgroundTo assess prognostic and predictive effects of clinical and biochemical factors in our published randomized study of a weekly low dose (metronomic arm) versus a conventional dosage of zoledronic acid (conventional arm) in breast cancer patients with bone metastases.MethodsTreatment outcome of 60 patients with bone metastases were used to assess impacts of following potential prognostic factors, estrogen receptor status, lymph node status, 2 year-disease free interval (DFI), numbers of chemotherapy regimens administered, interventions, and serum levels of VEGF, N-telopeptide of type I collagen (NTx), CEA, and CA 15-3.ResultsIn univariate analyses, patients pretreated with 2 or fewer chemotherapy regimens, ER-positive tumors, 3 or fewer lymph nodes, DFI of more than 2 years, serum VEGF of less than 500 pg/mL after 3 months of intervention, serum CEA and CA 15-3 of less than ULN, and baseline serum NTx of less than 18 nM BCE had significantly longer progression free survival (PFS). The multivariate analysis showed that ER positivity (hazard ratio [HR], 0.295; 95% confidence interval [CI], 0.141-0.618; P = 0.001), serum VEGF of less than 500 pg/mL after 3 months of intervention (HR, 2.220; 95% CI, 1.136-4.338; P = 0.020), baseline serum NTx of less than 18 nM BCE (HR, 2.842; 95% CI, 1.458-5.539; P = 0.001), and 2 or fewer chemotherapy regimens received (HR, 7.803; 95% CI, 2.884-21.112; P = 0.000) were associated with a better PFS. When evaluating the predictive effect of the biochemical factors, an interaction between NTx and zoledronic acid intervention was shown (P = 0.005). The HR of weekly low dose versus a conventional dosage of zoledronic acid was estimated to be 2.309 (99% CI, 1.067-5.012) in patients with baseline serum NTx of more than 18 nM BCE, indicating a superiority of weekly low dose of zoledronic acid.ConclusionsER, serum VEGF level after intervention, and numbers of chemotherapy regimens administered are prognostic but not predictive factors in breast cancer patients with bone metastases. Patients with baseline serum NTx of more than 18 nM BCE might benefit more from weekly low-dose of zoledronic acid.Trial registrationClinicalTrials.gov unique identifier: ClinicalTrials.gov: NCT00524849
Highlights
To assess prognostic and predictive effects of clinical and biochemical factors in our published randomized study of a weekly low dose versus a conventional dosage of zoledronic acid in breast cancer patients with bone metastases
Bone metastases play a crucial role in this cancer entity and are an important cause of disability and morbidity. 70% of women with advanced disease suffer from bone metastases [1]
After completion of a randomized study comparing weekly low-dose zoledronic acid with conventional-dose zoledronic acid in breast cancer patients with bone metastases, it has shown an advantage for weekly low-dose zoledronic acid
Summary
To assess prognostic and predictive effects of clinical and biochemical factors in our published randomized study of a weekly low dose (metronomic arm) versus a conventional dosage of zoledronic acid (conventional arm) in breast cancer patients with bone metastases. Zoledronic acid (Zometa, Novartis) is the only and the most potent bisphosphonate indicated for the management of solid tumor with bone metastases [3,4]. While the use of zoledronic acid once every year is sufficient for the treatment of postmenopausal osteoporosis, dosing every 3-4 weeks has emerged as an appropriate established strategy for the prevention and management of bone metastases [5,6]. Despite the completion of a randomized weekly low dose of zoledronic acid therapy study in breast cancer patients with bone metastases, no clear recommendation concerning its use outside of clinical studies can be given. Metronomic low-dose zoledronic acid is more effective than the conventional regimen and generates sustained reductions in circulating VEGF and NTx levels, as well as stabilization of serum CA 15-3 levels, no significant benefit in survival after a relative short follow-up could be shown [8]
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