Background: Due to its high incidence, evaluating performance of care delivered to breast cancer patients is a crucial issue. The multidisciplinary panel E.Pic.A. (Economic Appropriateness of an Integrated Care Pathway) defined a set of key performance indicators (KPIs) to evaluate economic waste in breast cancer healthcare interventions. Methods: The E.Pic.A. panel identified the principal KPIs that are crucial within the breast cancer care pathway to evaluate the performance of care. KPIs were defined taking into account their reliability, validity, usability and feasibility of measurement through the linkage between multiple routine healthcare data sources. Results: Seven KPIs were identified: three on instrumental diagnostics, two on surgery and two on treatment. The three KPIs regarding instrumental diagnostics are aimed at assessing the inappropriateness of diagnostic tests performed before and after the index surgery. The two KPIs regarding surgery measure the inappropriateness of possible repeated interventions considering the time elapsed from the index surgery. The two KPIs regarding oncologic therapy measure the inappropriateness about the administration time of adjuvant therapy and radiotherapy considering the time elapsed from the index surgery. Conclusion: E.Pic.A methodology could help to evaluate economic waste in healthcare interventions with the objective of redirecting resources to interventions with greater value. (HTA & Market Access)