Cost-effectiveness of zoledronic (ZOL) acid plus endocrine therapy (ET) in premenopausal women with early breast cancer (EBC) from a Canadian perspective

Abstract

557 Background: The Austrian Breast and Colorectal Cancer Study Group Trial 12 (ABCSG-12) examined the efficacy of 3 years (yrs) of treatment with goserelin in combination with ET (anastrozole or tamoxifen) with or without ZOL 4 mg q6 mos in 1,803 premenopausal women with EBC (median age 45 yrs). After a median follow-up of 47.8 mos (max 84 mos), risk of disease-free survival (DFS) events was reduced by 36% (HR = 0.64; p = 0.01) in patients (pts) who received ZOL (ZOL+ET) compared with those who did not (ET). Methods: A Markov model was used to estimate the cost per quality adjusted life years (QALYs) gained of 3 years treatment duration of ZOL+ET versus ET-only in premenopausal women with EBC based on results of the ABCSG-12. A Canadian healthcare system perspective and a lifetime timeframe were used. Outcomes and cost of breast cancer recurrence were based on recent published studies. Results were generated under 2 scenarios regarding duration of benefit (reduction in risk of recurrence) with ZOL: (1) Benefits persist to maximum follow-up in ABCSG-12 (trial benefit); (2) Benefits persist until death (lifetime benefit). Results: The cost of 3 years of ZOL (medication and administration) is 4 191 $CDN. Under the lifetime benefit scenario, 73% of these costs are offset by savings in the cost of recurrences. Under the trial benefit scenario, 12% are offset. QALYs gained are 1.63 yrs and 0.52 yrs under the lifetime and trial benefit scenarios respectively; cost-effectiveness is 1 122 $CDN and 3 675 $CDN per QALY gained respectively, which is well below the 50 000 $CDN per QALY threshold frequently used to assess whether therapies are cost-effective. Conclusions: The combination of ZOL + ET is a cost-effective use of healthcare resources from a Canadian healthcare system perspective. [Table: see text]