Effect of zoledronic acid (Zol) compared with placebo on overall disease and bone lesion progression in patients (pts) with bone metastases from certain solid tumors: Stratification by baseline characteristics

Abstract

18541 Background: Zol has been shown to significantly reduce the risk of skeletal complications compared with placebo in pts with bone metastases from a wide range of solid tumors including a delay of bone lesion progression in pts with renal cancer. To assess whether Zol may reduce the risk of overall disease or bone lesion progression in pts with solid tumors other than breast, non-small cell lung, and prostate cancers, we conducted a retrospective analysis of pts enrolled in a large, randomized, controlled trial. Methods: Pts treated with Zol or placebo were retrospectively stratified by baseline characteristics, including Brief Pain Inventory (BPI) composite pain score, time from initial cancer diagnosis to development of bone metastases, and duration of cancer. The relative risk (RR) of disease progression during 25 months on study was analyzed using the Cox proportional hazards model (stratified log rank). Results: Median baseline BPI pain score was 2.75, median time with cancer was 15 months, and median time to development of bone metastases was 8.5 months. In pts with a baseline BPI score ≥ 2.75 (n = 236), Zol treatment significantly reduced the RR of disease progression by 34% (hazard ratio [HR] = 0.657; P = .014) and the RR of bone lesion progression by 32% (HR = 0.680; P = .028) compared with placebo. Additionally, in pts with cancer duration <15 months (n = 193), Zol treatment reduced the RR of disease progression by 45% (HR = 0.547; P = .002) and the RR of bone lesion progression by 40% (HR = 0.605; P = .016) compared with placebo. Similarly, among pts who developed bone metastases < 8.5 months from initial diagnosis of cancer (n = 193), Zol treatment significantly reduced the RR of disease progression by 39% and the RR of bone lesion progression by 48% compared with placebo (HR = 0.611; P = .009 and HR = 0.519; P = .004, respectively). Conclusions: This exploratory analysis suggests that Zol has potential antitumor effects that may reduce the risk of overall disease and bone lesion progression in pts who have higher pain scores and shorter time to development of bone metastases. Prospective studies are needed to confirm this result. [Table: see text]