Economic evaluation of adjuvant hormonal options in postmenopausal women with breast cancer: Tamoxifen vs tamoxifen then exemestane vs anastrazole

Abstract

Listen

Translate article

6040 Background: Adjuvant anastrazole (ANA) for 5 years or tamoxifen followed by exemestane (TAM-EX) for 2.5 years each have become acceptable alternatives to tamoxifen (TAM) for 5 years in postmenopausal women with breast cancer. An economic evaluation was undertaken to compare the cost-effectiveness (CE) of ANA and TAM-EX relative to TAM alone. Methods: A Markov model was developed to calculate cumulative costs and disease free survival years (DFSY) for each alternative over 5- and 20-year time horizons. The analysis took a direct payer perspective. Drug costs were based on average wholesale prices in Canada in 2004. Costs of adverse events and relapses were not included in the primary analysis. The baseline TAM DFS rate and hazard ratios associated with ANA and TAM-EX were taken from the published ATAC and IES trials. Beyond the 5-year treatment period, hazard ratios for ANA and TAM-EX were set to 1.0, reflecting conservative estimates of benefit. Both costs and benefits were discounted at 3%. Results: Both ANA and TAM-EX were associated with gains in DFS. Per 1,000 patients treated, ANA resulted in an incremental gain of 56.4 DFSY after 5 years and 162.3 DFSY after 20 years relative to TAM alone. TAM-EX had an incremental gain of 31.6 and 164.9 DFSY per 1,000 treated relative to TAM alone after 5 and 20 years, respectively. Incremental costs were $6.35 million per 1,000 treated with ANA and $2.90 million per 1,000 treated with TAM-EX. The CE of ANA relative to TAM alone was $112,510 per DFSY after 5 years and $39,124 per DFSY after 20 years. The CE of TAM-EX relative to TAM alone was $91,604 and $17,570 per DFSY after 5 and 20 years. Comparing TAM-EX and ANA directly, ANA had an incremental cost of $139,174 per DFSY gained at 5 years and was dominated by TAM-EX at 20 years. Conclusions: Although the short-term CE of ANA and TAM-EX is unfavourable, projecting the benefits over a longer horizon results in CE ratios well below $50,000 per DFSY gained. Both alternatives appear to be cost-effective options for postmenopausal women with breast cancer. These results will be updated based on the recently reported DFS and adverse events rates of the ATAC and IES trials. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration AstraZeneca Pfizer