Cost utility analysis of early adjuvant letrozole or anastrozole versus tamoxifen in postmenopausal women with early invasive breast cancer: the UK perspective

Five years with the aromatase inhibitors letrozole or anastrozole is clinically superior to 5 years tamoxifen in postmenopausal women with early breast cancer. This paper analyses the cost-effectiveness of the aromatase inhibitors compared to tamoxifen using the same health economic model. A Markov model describes lifetime incidence of breast cancer events and treatment-related adverse events. Probabilities of disease progression, adverse events, and utility values were estimated using secondary sources; costs of breast-cancer care were obtained from a primary costing study. The incremental cost per QALY gained of letrozole vs. tamoxifen is £10,379 (95% CI £6,705–23,574), and of anastrozole versus tamoxifen is £11,428 (95% CI £6,211–48,795). If a 5-year carry over effect for the reduction in breast cancer events is assumed, the incremental costs per QALY gained compared to tamoxifen are £6,253 (95% CI £3,675–14,766) for letrozole and £7,015 (95% CI £3,316–31,997) for anastrozole. Five years of letrozole or anastrozole therapy is cost-effective in postmenopausal women with early breast cancer. Though the respective confidence intervals show significant overlap, letrozole has a 95% probability of being more cost-effective than tamoxifen at a £20,000 QALY value, whilst anastrozole has an 85% probability.