Cost-effectiveness of extended adjuvant letrozole after five years of tamoxifen in postmenopausal early breast cancer

Abstract

6044 Background: The MA17 study was a randomized double-blind placebo-controlled trial of 5 years of letrozole (Femara®) 2.5 mg/d in 5187 postmenopausal women (median age 62 yrs) with early breast cancer after 5 years of adjuvant tamoxifen. Due to significant improvement in disease-free survival with letrozole (92.8% vs 86.8%, P≤.001) and a trend toward an improvement in overall survival (96.0% vs 93.7%, P=.25), the study was unblinded at the first interim analysis (mean follow-up 2.4 years). The cost-effectiveness of extended adjuvant letrozole has not been examined. Methods: A Markov model of the natural history of breast cancer (Karnon, 2002) was adapted to evaluate the cost-effectiveness of extended adjuvant letrozole 2.5 mg/d in postmenopausal women. Probabilities of disease progression (locoregional and distant recurrence, new contralateral tumor) and death were estimated using published results of the MA17 trial (Goss, 2003) and other published studies. Costs of letrozole therapy and other breast cancer care (surveillance, treatment of recurrence and new contralateral tumor, death) and utility values were estimated from published sources. Cost-effectiveness was calculated as the ratio of the difference (letrozole vs no treatment) in expected lifetime costs to the difference in life years (LYs) and quality-adjusted LYs (QALYs) respectively; 95% CIs were estimated by probabilistic sensitivity analysis. Costs, LYs, and QALYs were discounted at 3% annually. Results: Letrozole therapy is estimated to result in an additional 0.53 LYs per patient (13.94 vs 13.41) and a similar gain in QALYs (12.49 vs 11.96). Expected lifetime costs of breast cancer care are estimated to be $9,350 greater with letrozole ($30,580 vs $21,240 with no treatment). Cost per LY gained with letrozole vs no treatment is $17,640 (95% CI $9,680 to $58,970). Cost per QALY gained is similar. Conclusions: Preliminary analyses based on published results of MA17 suggest that, compared with other generally-accepted treatments for early breast cancer (Earle, 2000), extended adjuvant letrozole is cost-effective while providing a 43% reduction in risk of recurrence. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Novartis Pharmaceutical Corp. Novartis; Pfizer Pfizer Novartis