Cost-effectiveness of adjuvant systemic therapy in low-risk breast cancer patients with nodal isolated tumor cells or micrometastases

The cost-effectiveness of adjuvant systemic therapy in patients with low-risk breast cancer and nodal isolated tumor cells or micrometastases is unknown. A cost-effectiveness analysis of adjuvant systemic therapy was carried out using the costs per 1% event prevented after 5 years of follow-up as incremental cost-effectiveness ratio (ICER). Secondary objective was to establish when adjuvant systemic therapy becomes cost saving. Patients included in the MIRROR study with isolated tumor cells or micrometastases who had a complete 5-year follow-up and who either did or did not receive systemic therapy were eligible. Sensitivity analyses were carried out. In the no adjuvant therapy cohort (N = 366), 24.9% of patients had an event within 5 years versus 16.8% of patients in the adjuvant therapy cohort (N = 483) (P <0.01). The ICER was euro363 per 1% event prevented. Beyond 18 years after diagnosis, the extrapolated mean cumulative costs per patient in the no adjuvant therapy cohort exceeded those of the adjuvant therapy cohort. In this population of breast cancer patients with isolated tumor cells or micrometastases, euro36 300 had to be invested to prevent one event in 5 years of follow-up. Adjuvant systemic therapy was cost saving beyond 18 years after diagnosis.