Trastuzumab is a standard treatment of HER2-positive early breast cancer in many countries, and it is usually given as a one year adjuvant treatment. However, its cost-effectiveness has not been assessed in Finland. The Finland Herceptin (FinHer) trial has compared a shorter 9-week treatment protocol against no trastuzumab with promising results. The aim of this study was to assess the potential cost-effectiveness of the 9-week treatment based on the recently published five-year follow-up results of the FinHer trial.

An evaluation model of breast cancer treatment was constructed using fitted survival estimates and a long-term Markov model. The cost-effectiveness of 9-week adjuvant treatment was assessed in a Finnish setting, compared to treatment without trastuzumab. The analysis was performed from a societal perspective, and a 3% discount rate was applied for future costs and outcomes. Value of information analysis was performed to estimate the potential value of further research.

According to the probabilistic analysis, the incremental cost-effectiveness ratio was €12 000 per quality adjusted life year (QALY), and €9300 per life year gained (LYG), when comparing adjuvant trastuzumab therapy to standard treatment without trastuzumab. The modelled incremental outcomes for trastuzumab treatment were 0.66 QALY and 0.85 LYG for a lifetime perspective. Value of information analysis showed that additional research on treatment effects would be most valuable for reducing uncertainty in the adoption decision.

Adjuvant 9-week trastuzumab is likely to be a cost-effective treatment in the Finnish setting. Results from an ongoing trial comparing adjuvant 9-week treatment with the 12-month treatment will play a key role in addressing the uncertainty related to the treatment effect and potential cost-effectiveness of these two treatment protocols.