The efficacy of sequential adjuvant trastuzumab (aTZ) after chemotherapy in women with early-stage human epidermal growth factor-2 (HER2/neu)-positive breast cancer reported by the updated Herceptin Adjuvant (HERA) trial appears less favorable than originally reported. Based on these updated results, we estimated the cost-utility (CU) of sequential aTZ relative to chemotherapy alone in terms of incremental cost per quality-adjusted life-year (QALY) gained.
A Markov model estimated incremental costs and outcomes of 12 months of aTZ after adjuvant chemotherapy in women with HER2/neu-positive breast cancer over a 25-year horizon. The model incorporated four broad health states (disease-free, local recurrence [LCR], distant recurrence [DCR], death), stratified with or without symptomatic cardiotoxicity. Baseline event rates and 3-year relative risk (RR = 0.75) were derived from the HERA trial. As the duration of the benefit remains uncertain, the analysis considered 5-year and 3-year duration of benefit in two scenarios. Costs and utility weights were from the literature. The analysis took a direct payer perspective, with costs reported in 2007 Canadian dollars. Costs and QALYs were discounted by 3% annually.
The mean CU of sequential aTZ at a 25-year horizon was $72,292 per QALY gained in the 5-year scenario and $127,862 per QALY gained in the 3-year scenario. Results were particularly sensitive to the magnitude and duration of carryover benefit.
The CU of sequential aTZ is primarily dependent on the magnitude and duration of benefit. Further clinical research is required to establish the optimum sequence and duration of aTZ therapy and clarify the magnitude and duration of treatment benefit.