Healthcare costs and health outcomes analysis of neoadjuvant Trastuzumab therapy for human epidermal growth factor receptor 2 (HER2) positive breast cancer

Background Globally, the incidence of breast cancer continues to rise; however, mortality rates are declining due to the growing effectiveness of targeted therapies and treatments. Overexpression of human epidermal growth factor receptor 2 ( HER2 ) is seen in ∼15% of breast cancers (termed HER2+ ). Trastuzumab is the standard HER2 -targeted therapy for HER2+ breast cancers in the adjuvant setting, and is increasingly being used as a neoadjuvant chemotherapy treatment (NACT or NAC). However, as well as the clinical impact, using drugs in a different treatment setting (including neoadjuvant therapy) has a financial impact. Economic evaluation of novel chemotherapeutic strategies can assess both clinical utility and cost-effectiveness, thereby informing and guiding healthcare resource allocation decisions. Currently, the cost, clinical outcomes, and cost-effectiveness of single-agent neoadjuvant Trastuzumab remain underexplored. In this study, we evaluated the cost-effectiveness of Trastuzumab administered as neoadjuvant therapy, adjuvant therapy, or a combination of both regimens (NACT/ACT). Methods A 3-year retrospective observational comparative analysis was conducted to examine costs and health outcomes using clinicopathological data (treatment type, surgical procedure, breast cancer subtype) from a public hospital in Ireland. Overall, 192 non-metastatic, non-palliative HER2+ breast cancer patients (Luminal B HER2 , and HER2+ [non-luminal]) were selected (151 adjuvant Trastuzumab treated, 28 neoadjuvant Trastuzumab treated, 13 NACT/ACT Trastuzumab treated). The analysis estimated the cost of treatment (chemotherapy regimen, surgery type) and health outcomes, which were evaluated by analysis of survival data, and by calculating quality-adjusted life years (QALYs) and average cost-effectiveness ratios (ACERs). Multivariate regression analysis, using survival regression model techniques, was performed to evaluate associations between treatment types and total costs-adjusted by age, stage, grade, and subtype. A Cox proportional hazard model estimated the effect of treatment alternatives for time to disease-free survival (DFS). Results Multivariate analysis demonstrated no significant difference in treatment cost ( p = 0.318), surgery cost ( p = 0.951), or DFS ( p = 0.236) between the adjuvant and neoadjuvant Trastuzumab treatment groups. A significantly higher treatment cost was observed in older patients ( p = 0.011) and patients with Grade 3 tumours ( p = 0.037). No significant difference in cost was found between the HER2 subtype groups ( p = 0.129) or between disease stages ( p = 0.71). No statistically significant difference in QALY was observed between adjuvant and neoadjuvant treatment groups ( p = 0.296). Conclusion Overall, while adjuvant Trastuzumab remains the most cost-effective strategy for patients with HER2+ breast cancer, adopting a neoadjuvant Trastuzumab approach does not appear to pose a significant economic disadvantage. Notably, higher treatment costs were observed among older patients, a finding with important financial implications for healthcare systems. These results highlight the need for careful evaluation to inform forthcoming age-related cancer policy updates.