Practice patterns in bone modifying agent utilization: An analysis in patients with metastatic cancer and bone involvement at an NCI-designated center.

Abstract

62 Background: Bone modifying agents (BMA) can reduce skeletal related events for patients with metastatic cancer and bone involvement. ASCO supports use of Zoledronic acid (ZA) and Denosumab (DB), with specific endorsement of both an every 3 to 4-week (Q1 month) and every 12-week (Q3 month) schedule for ZA in metastatic breast cancer. Trends in BMA utilization may identify areas to improve value in cancer care. Methods: We retrospectively reviewed utilization of BMAs at Seattle Cancer Care Alliance/University of Washington from fiscal year 2015-2019. We identified 1,286 patients who underwent 12,594 administrations. Data was categorized by BMA (ZA acid vs DB) and disease group. A 45-day cutoff defined interval of treatment (Q1 vs Q3). Whole-sale acquisition cost (WAC) and administration costs were estimated from CMS allowed charges. We calculated total costs spent during time period and projected potential savings for switching from Q1 to Q3 ZA administration. Results: A total of 904 patients received ZA (7201 administrations) and 473 patients received DB (5,393 administrations). The breast, myeloma, prostate, and kidney groups accounted for 81% of administrations. In breast, 427 patients received ZA (1,761 administrations) and 411 patients received DB (2,708 administrations). Among all patients, DM and ZA administrations remained constant over time, however, in breast, there was a trend towards less DB and more ZA administrations. The administration frequency (Q1 vs Q3) for both drugs stayed constant in the total cohort. Among ZA administrations in breast, there was a reversal in the trend for Q1 vs Q3, with Q1 being most common in 2015, and Q3 the most common in 2019 (crossover in 2018 fiscal year). In breast, 30 patients transitioned from Q1 to Q3, with majority occurring before 2017 ASCO update. Total costs on BMA utilization was estimated as $11,672,189,80, 90% attributable to DB. The projected savings for switching from Q1 to Q3 ZA administration was $1,223,961.08. Conclusions: BMA prescribing patterns from 2015-2019 show no change in ZA and DB utilization, though a trend towards increased ZA and decreased DB use in breast cancer was observed. There was a transition in practice patterns to adopt the Q3 ZA administration over time, however, the uptake of this has been incomplete. It is hoped that raising awareness of these practice patterns will lead to adoption of guideline-based decision making and promote value-based cancer care.