Economic evaluation of letrozole in the treatment of advanced breast cancer in postmenopausal women in Canada.

OBJECTIVE To determine the cost-effectiveness of initiation of second-line hormone therapy with letrozole in the treatment of advanced breast cancer in postmenopausal women in Canada, compared to megestrol acetate. METHODS A modified Markov model, incorporating seven health states, was designed to simulate the treatment of patients with advanced breast cancer from second-line hormone therapy to death. The model was constructed with data from a clinical trial, literature sources, and interviews with breast cancer treatment experts. Canadian experts provided information on resource utilization patterns and local costs were attached to these resources. The model was used to calculate mean survival time, time without progression, and total direct medical costs for patients initiating treatment with letrozole 2.5 mg or megestrol acetate 160 mg. RESULTS The mean survival time and time without progression for letrozole 2.5 mg patients were 28.3 months and 19.0 months, respectively, compared to 25.7 months and 16.5 months for megestrol acetate 160 mg patients. Total treatment costs for both groups were similar with the letrozole 2.5 mg group costing dollar 20,068 per patient, dollar 1061 more than the megestrol acetate 160 mg group (dollar CAN, 1996). The cost-effectiveness ratio for letrozole 2.5 mg with respect to megestrol was dollar 5051 per year of life gained. Sensitivity analysis showed that this ratio was sensitive to variations in the probabilities governing disease progression. CONCLUSIONS Advanced breast cancer patients initiating second-line hormone therapy with letrozole 2.5 mg have better clinical outcomes than patients receiving megestrol acetate 160 mg. Furthermore, this benefit comes at an acceptable cost to the Canadian health care system.