OBJECTIVES: The primary objective is to estimate the benefit of adjuvant trastuzumab in the treatment of patients with HER2-positive early breast cancer (HER2+ eBC) in terms of life years gained (LYG) and disease-free life years gained (DFLYG), since its approval in Spain in 2006. The secondary objective is to estimate the incremental cost for the healthcare system, and to compare both parameters.

METHODS: An epidemiological model that compared two scenarios (with and without trastuzumab) was developed to estimate the benefits and costs associated with adjuvant trastuzumab in HER2+ eBC patient cohorts from 2006 to 2017, with a time horizon until 2035 and a 3% discount rate for both parameters. The effectiveness data used to model the survival curves were obtained from the T (trastuzumab)+CT (chemotherapy) and CT arms of the phase-III BCIRG-006 study. The analysis included direct costs related to the adjuvant treatment (pharmacological, administration and monitoring) and disease recurrence management.

RESULTS: A total of 35,851 women make up the cohorts from 2006 to 2017. The sum of life years (LY) in the T+CT scenario was 605,358 (525,964 DFLY) versus 564,137 (489,916 DFLY) in the CT scenario, resulting in an estimated 41,221 LYG (36,048 DFLYG) provided by trastuzumab. The general population for the same age range would have generated 704,331 LY. The estimated incremental cost was 880.43 million€ (€24,558.13 per patient) from 2006 to 2035. The incremental cost-effectiveness ratios obtained were €20,644 and €23,960 per LYG and DFLYG, respectively.

CONCLUSIONS: Our estimations show that adjuvant trastuzumab has substantially improved the survival of patients with HER2+ eBC, contributing over 41,000 LYG to the Spanish society (over 36,000 DFLYG) in an acceptable cost-effective manner. However, the sum of LYG with trastuzumab is still far from the LY estimated for the general population, supporting the need of further advances in HER2+ eBC therapy.