Cost-benefit analysis of endocrine therapy in the adjuvant setting for postmenopausal patients with hormone receptor-positive breast cancer, based on survival data and future prices for generic drugs in the context of the German health care system

Background: Cost-effectiveness analyses have focused on aromatase inhibitors (AIs), but the results are inconsistent and disease-free survival has often been extrapolated to overall survival. The present study calculates the cost-effectiveness of 5 years of letrozole versus tamoxifen versus anastrozole in the context of the German health care system, using survival data from the Breast International Group (BIG) 1-98 study and the Arimidex, Tamoxifen, Alone or in Combination (ATAC) study and generic prices.

Materials and Methods: A hybrid model was developed that incorporates recurrence rates, overall survival, treatment costs and treatment-associated adverse events and the resulting costs. The basic assumption was that generic anastrozole would lead to a price reduction to 75% of the original price. Further analyses were carried out with 50% and 25% of the original prices for anastrozole and letrozole.

Results: The cost-benefit model showed a gain of 0.3124 or 0.0659 quality-adjusted life years (QALYs) for letrozole or anastrozole. Incremental costs of 29,375.15/QALY for letrozole (100% of original price) were calculated and 94,648.03/QALY for anastrozole (75% of original price). Marked increases in cost-effectiveness are observed with further decreases in price (anastrozole: 50% price 54,715.17/QALY, 25% price 14,779.57/QALY; letrozole 75% price 20,988.59/QALY, 50% price 12,602.03/QALY, 25% price 4,215.46/QALY).

Conclusion: The present model including the inverse probability of censoring weighted analysis (IPCW) for letrozole and generic prices for both AIs shows that letrozole is cost effective.