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 tarnoxifen 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. tarnoxifen is -10,379 pound (95% CI 6,705-23,574) pound, and of anastrozole versus tamoxifen is pound 11,428 (95% CI 6,211-48,795) pound. 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 pound (95% CI -3,675-14,766) pound for letrozole and 7,015 pound (95% Cl -3,316-31,997) pound 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 tarnoxifen at a 20,000 pound QALY value, whilst anastrozole has an 85% probability.