Use of intravenous bisphosphonates in patients with breast, lung, or prostate cancer and metastases to bone: a 15-year study in two large US health systems

Abstract

The purpose of this paper is to document the use of intravenous (IV) bisphosphonates for prevention of skeletal-related events (SREs) in patients with bone metastases (BM) due to breast cancer (BC), lung cancer (LC), or prostate cancer (PC). Using data from two large US health systems, we identified all patients aged ≥ 18 years with primary BC, LC, or PC and newly diagnosed BM between 1/1/1995 and 12/31/2009. Starting with the diagnosis of BM, we reviewed medical and administrative records for evidence of receipt of IV bisphosphonates (zoledronic acid or pamidronate) and occurrence of SREs. Initiation of IV bisphosphonates prior to occurrence of an SRE was designated "primary prophylaxis"; use following an SRE was designated "secondary prophylaxis". We identified a total of 1,193 patients with newly diagnosed BM, including 400 with BC, 332 with LC, and 461 with PC. Use of IV bisphosphonates was substantially higher in BC (55.8 % of all patients) than in LC (14.8 %) or PC (20.2 %). Use of IV bisphosphonates was fairly evenly split between primary and secondary prophylaxis in BC (26.3 vs. 29.5 %, respectively) and PC (10.6 vs 9.5 %); in LC, however, primary prophylaxis was much less common than secondary prophylaxis (4.8 vs 9.9 %). Almost one half of all patients with BM due to BC, and substantially more with LC and PC, do not receive IV bisphosphonates. Among patients receiving such therapy, treatment often is not initiated until after the occurrence of an SRE. Our study suggests that IV bisphosphonates may be substantially underutilized in patients with BM due to these common cancers.