The model-based cost-effectiveness analysis of 1-year adjuvant trastuzumab treatment: based on 2-year follow-up HERA trial data

Background Several randomized controlled trials have confirmed the usefulness of trastuzumab as an adjuvant therapy for HER2-overexpressed breast cancer patients; however, the costs for 1-year treatment are high. Therefore, we performed an economic analysis regarding the efficient distribution of medical resources. Methods To analyze the cost-effectiveness for a 1-year adjuvant trastuzumab treatment group compared with the observation group, we constructed a Markov model adopting a 3% per year discount rate for costs and outcomes. The time horizon was 50 years. The perspective was that of health-care payers, as only direct medical costs were calculated. The outcome was measured as life-year gained (LYG) from 2-year follow-up HERA trial data. Results The ICER of the standard setting (5 years efficacy and 50–60 kg patient weight) was JPY 2,600,000 (€17,000) per LYG. The calculation results of other weight class ICER were JPY 2,200,000 (€15,000) and JPY 3,300,000 (€22,000) per LYG for the patients, respectively, who weighed less than 50 kg, and 60–75 kg. In the sensitivity analysis, the period of trastuzumab efficacy was the most influential parameter for the result of cost-effectiveness. However, even if the trastuzumab efficacy were to continue for only 2 years, at least, which is a conservative setting judging from the joint analysis (NSABP B-31 and NCCTG N9831 trials), the ICER remains acceptable for any weight class. Conclusion These results suggest that the 1-year adjuvant trastuzumab treatment is cost-effective. Both clinical and economic benefits were superior for the 1-year adjuvant trastuzumab treatment group compared with the observation group.