PCN67 Cost Effectiveness of Zoledronic Acid (ZOL) in Postmenopausal Women With Early Breast Cancer Receiving Adjuvant Letrozole From German and Italian Perspectives

Abstract

In the ZO-FAST trial, postmenopausal women with early breast cancer (pmBCa) and a bone mineral density (BMD) T-score ≥–2 and receiving adjuvant Letrozole (2.5 mg/day) were randomized to either immediate ZOL (4 mg/6 months) treatment (“Upfront ZOL”) or to the same therapy but only when BMD T-score decreased to <−2 or fracture occurrence (“Delayed ZOL”). After 60 months, Upfront ZOL increased both BMD and disease-free survival (P<.05) relative to Delayed ZOL. The present analysis assessed the cost effectiveness of Upfront vs. Delayed ZOL in this population, from German (DE) and Italian (IT) payer perspectives. A Markov state-transition model was constructed to estimate the lifetime costs and QALY for hypothetical cohorts of pmBCa women receiving Letrozole with Upfront or Delayed ZOL. Consistent with ZO-FAST, at baseline, patients were 57 years old and BCa-recurrence free. Patients could progress over time to “Local Recurrence”, “Contralateral Tumor”, “Distant Recurrence”, or Death. Annual transition probabilities were derived from ZO-FAST, supplemented with literature estimates. Direct costs and utilities were literature-based. All results were discounted using country-specific rates. In IT, Upfront ZOL treatment was associated with 15.01 QALYs and €21 998. Delayed ZOL was associated with 13.98 QALYs and €19 458. Thus, Upfront ZOL cost €2 453/QALY. In DE, Upfront ZOL treatment resulted in 15.44 QALYs and €24 032. Delayed ZOL was associated with 14.37 QALYs and €23 081. Therefore, Upfront ZOL cost €888/QALY. In both countries, the results were very insensitive to changes in individual model input values. Compared to Delayed ZOL, Upfront ZOL treatment cost ≤€20 000/QALY in >95% of 1000 probabilistic sensitivity analysis model runs in both IT and DE. This analysis suggests that treatment with Upfront ZOL may reduce recurrence and increase QALY and is highly cost effective relative to a Delayed ZOL strategy from an IT and DE health care perspective.