Objectives

To systematically summarize evidence on the economic burden of human epidermal growth factor 2-positive (HER2+) advanced or metastatic breast cancer (mBC) and economic evaluations of first-line (1L) treatments for hormone receptor-positive (HR+)/HER2+ mBC.

Methods

A systematic literature review (SLR) was conducted in accordance with PRISMA guidelines. Real-world studies (RWS) evaluating healthcare resource utilization, direct and indirect costs in HER2+ mBC, and economic models evaluating 1L treatment for HR+/HER2+ mBC published from 01/2000-05/2021 in MEDLINE, Embase, and Cochrane Library were included.

Results

Among 813 records screened, 32 RWS of economic burden and 8 economic evaluations were selected. Economic burden studies encompassed 30 retrospective observational studies, 1 prospective observational study, and 1 cross-sectional survey. Patients with HER2+ mBC incurred high direct medical costs, most prominently attributed to treatment costs. High direct medical costs were incurred during the first year after mBC diagnosis and after disease progression, compared to stable disease. Few studies stratified costs by HR biomarker status.

Economic evaluations included 6 cost utility analyses (CUA) in the UK (n=3) and Canada (n=3), 1 cost effectiveness analysis (CEA) in Australia and 1 cost-of-illness (COI) study in Spain. Four CUAs applied a partitioned survival model, 1 CUA applied a Markov model, and the CEA used a decision tree. Other studies did not specify model structure. Included studies varied across treatment strategies, evaluated interventions, patient population, HTA setting. The CUAs and CEA compared anti-HER2 therapy (AHT) + endocrine therapy (ET) or AHT + chemotherapy with another AHT+ET, AHT, or ET alone. Indirect costs were infrequently included.

Conclusions

The evidence on economic burden specific to HR+/HER2+ mBC, though limited, is heterogeneous. The findings of this SLR suggest further research is needed to uncover the full patient and societal cost burden economic burden of HR+/HER2+ mBC in the 1L setting.