Breast cancer (BC) is a global concern, with Peru experiencing a high incidence and mortality. Trastuzumab, a crucial treatment for human epidermal growth factor receptor 2-positive BC, is administered intravenously or subcutaneously (SC). This study evaluates the costs associated with both methods at Peru's Instituto Nacional de Enfermedades Neoplásicas. Real data indicate that SC administration reduces treatment costs by approximately S/15,049.09. Cross-continental comparisons highlight a global trend favouring SC administration for efficiency and cost-effectiveness. The analysis provides insights for informed decision-making in resource-constrained healthcare settings like Peru, emphasising the need to consider local contexts in optimising oncology care.

Purpose: In Peru, breast cancer (BC) stands as the most predominant malignancy neoplasm among women. Trastuzumab has marked a significant milestone in the management of this disease. It has been shown to improve prognosis in human epidermal growth factor receptor 2 (HER2)-expressing female patients, but its repercussions and efficacy are yet to be analyzed in a context with limited resources. Methods: The study population is made of woman patients aged 18 years and older diagnosed with HER2-positive BC at Instituto Nacional de Enfermedades Neoplásicas (INEN, Lima, Peru) during 2019-2021 and treated with at least one dose of subcutaneous trastuzumab. We reviewed medical records to register treatment characteristics, adverse events (AEs), disease progression, and survival status. We considered a median follow-up time of 36 and 45 months for progression and survival status. Results: The ma...