Cost effectiveness of extended adjuvant letrozole in postmenopausal women after adjuvant tamoxifen therapy: the UK perspective

BACKGROUND: MA17 was a randomised placebo-controlled trial of letrozole 2.5 mg/day in 5187 estrogen receptor-positive, 50% node-negative, postmenopausal women (median age 62 years at enrollment) with early breast cancer, post-5 years' adjuvant tamoxifen therapy. The objective of this evaluation was to extrapolate the findings from the MA17 trial to estimate the lifetime cost effectiveness of letrozole in this setting. METHODS: A Markov model was used to estimate the incremental cost per QALY gained with extended adjuvant letrozole versus no therapy. Probabilities of disease progression and death were estimated using data from the MA17 study and other secondary sources. Costs of breast cancer care (letrozole therapy, surveillance, recurrences, terminal care) and treatment of osteoporosis and utilities were derived from literature. A full probabilistic sensitivity analysis was undertaken. The analysis was conducted from the perspective of the UK National Health Service (NHS) and cost estimates reflect 2004 values. All costs and outcomes were discounted at 3.5%. RESULTS: Extended adjuvant letrozole resulted in a gain of 0.36 QALYs per patient (13.66 vs 13.30 with no therapy). These benefits were obtained at an additional expected lifetime cost of 3732 pounds per patient (10,833 pounds letrozole vs 7101 pounds with no therapy). Cost effectiveness was estimated at 10,338 pounds per QALY gained (95% CI 5276, 43,828). The results were robust to sensitivity analyses. CONCLUSION: Five years of letrozole therapy appears to be cost effective from the NHS perspective and should be considered in women with early breast cancer, following tamoxifen adjuvant therapy.