Study Oversight
We also performed exploratory analyses to investigate treatment effects on sites of first recurrence. After a protocol amendment was approved before the first interim analysis in 2008, we added another secondary end point: invasive-disease–free survival, which was defined according to the Standardized Definitions for Efficacy and End Points in Adjuvant Breast Cancer Trials (STEEP) guidelines. The date of recurrence was defined as the date on which relapse was first suspected, rather than the date on which it was confirmed, to reduce the risk of ascertainment bias. On-site and telephone-based monitoring was performed to ensure that recurrence dates were backdated to the date on which the event was first suspected, when this date preceded clinical, histologic, or imaging confirmation. Viagra Australia website
Study Oversight
The study was sponsored by the University of Sheffield and approved as a United Kingdom national trial by the Clinical Trials Advisory Awards Committee. Grant support was provided by Novartis Pharmaceuticals and was supplemented in the United Kingdom by the infrastructure of the National Cancer Research Network. Novartis Pharmaceuticals donated study supplies of zoledronic acid. The authors developed the study concept, wrote the protocol, and performed and reviewed all analyses. The study was conducted in accordance with the protocol, with amendments to reduce the risk of osteonecrosis of the jaw and to inform both patients and dental practitioners of this risk. The first author wrote the first draft of the manuscript, and all authors were involved in revision and approval of the manuscript. Novartis Pharmaceuticals was given an opportunity to comment on the manuscript, but all decisions on submission of the manuscript for publication were made by the authors and the trial steering committee.
Statistical Analysis
A final analysis was planned after the primary end point (disease-free survival) had occurred in 940 patients, on the basis of the recruitment of 3300 patients during a 3-year period, an anticipated rate of disease-free survival of 75% at 3 years, and a 5% annual rate of loss to follow-up. It was estimated that these numbers would provide a power of 80% to detect a relative reduction of 17% in the rate of disease recurrence or death among patients receiving zoledronic acid, at a two-sided level of significance of 0.05, which would approximate an absolute benefit of 3.7 percentage points.
A single interim analysis was planned after the primary end point had been reached in 470 patients, with a two-sided alpha level of 0.005. After this analysis was performed, on the advice of the independent data and safety monitoring committee, no efficacy data were released. Because the rate of events contributing to the primary end point was lower than predicted (resulting in a combined rate of disease-free survival of 85% at 3 years), an independent statistician who was unaware of the findings and was not involved in the first interim analysis provided revised stopping boundaries for both efficacy and lack of benefit that would allow timely release of a clinically important result. A second interim analysis was planned after the primary end point had occurred in at least 705 patients, along with a 0.5% probability of declaring false positive results (one-sided) or a 5.0% probability of declaring negative results with the use of a group sequential-design method.13 The analysis was carried out on 752 events, resulting in an efficacy boundary for the hazard ratio of 0.833 (lower boundary) and a lack-of-efficacy boundary of 0.936 (upper boundary). At this interim analysis, the lack-of-efficacy boundary was crossed, and the committee recommended the release of results.