Final analysis of dose density with zoledronic acid treatment in metastatic breast cancer patients: ZARAS study.

630 Background: Zoledronic acid (ZA), a highly potent bisphosphonate, has been shown to reduce/delay skeletal-related events (SREs) in patients (pts) with bone metastatic disease, and extending time to first skeletal complication, which can have a positive impact on the quality of life of pts with bone metastasis. Our aims were to determine treatment adherence, patterns of use (regular administration q 3-4 weeks) and maintenance doses of ZA in breast cancer pts with bone metastasis (mBC) in Spain. Methods: Retrospective observational, multicentric study. Data from 421 mBC pts died (before 31st of March 2009), were collected. 366 pts, with at least 3 consecutive doses of ZA treatment for their metastatic disease, were included in this final analysis report. Results: n= 366 pts. Median age was 57 years (28-86). Postmenopausal status 69.4%, ER+ 77%, HER2/neu+ 25,7%, PR+ 52,2%. 51,6% of pts had previous SREs. 50% pts received > 12 dose of ZA during the first year of treatment (optimal treatment); 32.5% during...