Purpose: To evaluate the cost-effectiveness of 12-month adjuvant trastuzumab therapy in women with high-risk human epidermal growth factor receptor 2 (HER2) -positive early breast cancer.
Methods: A Markov model tracked quarterly patients' transitions between five health states: disease free, local relapse, disease free after local relapse, metastatic disease, and death. Patients were allowed to incur symptomatic or asymptomatic transient cardiac dysfunction during trastuzumab administration. Probabilities were derived mainly from the combined report of the National Surgical Adjuvant Breast and Bowel Project B-31 and the North Central Cancer Treatment Group N9831 trials (95% node positive) and a meta-analysis by the Early Breast Cancer Trialists' Collaborative Group. Costs were estimated from the perspective of the Italian and US health care systems. The analysis was run during a 15-year time horizon. A 3% yearly discount rate was applied to both costs and life-years. Second-order Monte-Carlo and probabilistic sensitivity analyses were performed.
Results: Adjuvant trastuzumab increases life expectancy by 1.54 (1.18 discounted) quality-adjusted life-years (QALYs). At a cost of 675 euros and 767 dollars per weekly dose in the Italian and US setting, respectively, trastuzumab achieves its clinical benefit at a cost of 14,861 euros (95% CI, 3,917 euros to 44,028 euros) and 18,970 dollars (95% CI, 6,014 dollars to 45,621 dollars) per QALY saved. The incremental cost effectiveness was higher than 50,000 euros/QALY (or 60,000 dollars/QALY) at time horizons shorter than 7.8 years and for patients older than 76 years or with a 10-year risk of relapse lower than 15%. The results confirmed the cost effectiveness when simulating a Herceptin Adjuvant Trial (HERA) -like scenario at multiway sensitivity analysis.
Conclusion: In a long-term horizon, adjuvant trastuzumab is a cost-effective therapy for patients with HER2-positive, high-risk, early breast cancer.