Real-world efficacy of bone modifying agents (BMAs) in patients with breast cancer (BC) treated in an academic health system: Use of the “green button.

Abstract

e18054 Background: BC patients (pts) have a high incidence of bone metastases (mets) and associated morbidity. BMAs – zoledronic acid (ZA) and denosumab (Den) – reduce bone met related skeletal related events (SREs). ASCO guidelines do not recommend one over another, and survival and real-world outcome data to guide point-of-care decision-making is lacking. We used the previously developed “Green Button” informatics consult service, designed to rapidly test hypotheses when no applicable published data is available to guide treatment choices (Longhurst et al Health Affairs 2014), to compare BMA efficacy in BC patients. Methods: Patients treated for BC at Stanford HealthCare between 2009 - 2018, receiving standard of care cancer and BMA therapy, as determined by their oncologists, were identified who had > 2 electronic health records (EHRs) documenting BMA administration, and had either ICD9 174 or ICD10 C50 diagnostic codes. Pts were grouped into Den only, ZA only, or both. Two outcomes were analyzed: 1) SREs as a composite outcome of pathologic fracture (1st ICD10 M84.5); spinal cord compression (1st ICD10 M47.1 or G95.2), radiation therapy (1st CPT 77300) or hypercalcemia (calcium ≥10.5); and 2) death. Effects were compared relative to baseline treatment with ZA; we show results of log rank tests for differences in survival outcomes. Three analyses were performed: 1) Unadjusted analysis; 2) Basic matching analysis accounting for length of medical record, age, sex and year of treatment; 3) Propensity score matching using all available data; all prior to index treatment with either Den or ZA. Results: 802 patients had ≥ 2 records of BMA administration. Comparison of Den only and ZA only pts is shown in the table below. Median ages and length of medical record were balanced in all groups. Conclusions: This preliminary retrospective analysis of unsupervised BMA use suggests that Den is superior to ZA for the outcomes of interest; confirmatory analyses are underway.[Table: see text]