Patón, Víctor

6023 Background: The addition of trastuzumab (H) to a standard adjuvant therapy regimen (doxorubicin, cyclophosphamide, and paclitaxel; AC→T) is associated with a 52% reduction in risk (p < 0.0001) of disease recurrence in patients with HER2 positive operable breast cancer (Romond et al, NEJM 2005). A cost-effectiveness analysis was performed to assess the lifetime clinical and economic implications of this important clinical finding. Methods: A Markov model with three health states (disease-free survival [DFS], recurrence, and death) was used to estimate the likely cost-effectiveness (CE) for a 50 yr old woman. Efficacy results from both trials (NCCTG N9831/NSABP B-31) were used through 4 years, and projections of time to recurrence and death were based on the literature (EBCTCG, Lancet 2005). After 4 years, annual transition probabilities to recurrence and death are assumed to be the same in both arms. Cardiotoxicity was higher with H (Perez EA, ASCO 2005). Actual total dose of H was used which was lower than scheduled dose. Incremental costs associated with addition of H to adjuvant therapy were estimated using average wholesale prices, Medicare reimbursement rates and other published data. These costs included testing for HER2 status, drug and administration costs for H, cardiac monitoring, treatment of cardiotoxicity, treatment following recurrence, and end-of-life costs for dying patients. Utility estimates were derived from the literature. Results: Over a lifetime, the cost per quality-adjusted life year gained (QALY; discount rate 3%) is $27,800, with a range of $17,900 to $39,100 under multi-way sensitivity analysis. Projected life expectancy from the Markov model is 3 years longer for H patients (19.4 v 16.4 yrs). Over a 20-year horizon, addition of H to AC→T is estimated to cost an additional $46,300 on average, with an expected gain of 1.28 QALYs-a cost/QALY of $36,100. The key drivers of CE are the cost of treatment and the improvement in DFS. Conclusion: The model projects a cost-utility ratio that is below that of many treatments used for oncology patients. The use of trastuzumab in the adjuvant setting for HER2+ breast cancer is projected to be cost-effective. [Table: see text]