Cost-effectiveness of anastrozole compared to tamoxifen in hormone receptor-positive early breast cancer. Analysis based on the ATAC trial.

The 5-year completed treatment analysis of the Anastrozole and Tamoxifen-Alone or in Combination (ATAC) trial showed the superiority of anastrozole over tamoxifen for reduction of disease progression in patients with hormone receptor-positive (HR+) early breast cancer (EBC). The objective was to evaluate the cost-effectiveness of anastrozole versus tamoxifen in this setting. A health economic model was developed comparing the natural history of EBC patients treated with anastrozole or tamoxifen. The perspective of the Belgian health care system was taken. Disease progression from EBC was obtained from the ATAC trial and further progression beyond the clinical trial from published literature. Resource use data were obtained from the ATAC study and from published local retrospective data. Anastrozole was cost-effective versus tamoxifen, provided that a time horizon of at least 9 years is taken. This sensitivity to time horizon is inherently associated with the adjuvant setting due to the different evolution of costs and outcomes over time. Costs are incurred solely during the first 5 years, whereas outcomes are cumulated beyond adjuvant treatment. In conclusion, provided that a sufficient time horizon is taken and that long-term model predictions are confirmed from further follow-up from the ATAC study, anastrozole is a highly cost-effective adjuvant therapy compared to tamoxifen.