Clinical and economic outcomes of adding [18F]FES PET/CT in estrogen receptor status identification in metastatic and recurrent breast cancer in the US

Background and objectives Correct identification of estrogen receptor (ER) status in breast cancer (BC) is crucial to optimize treatment; however, standard of care, involving biopsy and immunohistochemistry (IHC), and other diagnostic tools such as 2-deoxy-2-[ 18 F]fluoro-D-glucose or 2-[ 18 F]fluoro-2-deoxy-D-glucose ([ 18 F]FDG), can yield inconclusive results. 16α-[ 18 F]fluoro-17β-fluoroestradiol ([ 18 F]FES) can be a powerful tool, providing high diagnostic accuracy of ER-positive disease. The aim of this study was to estimate the budget impact and cost-effectiveness of adding [ 18 F]FES PET/CT to biopsy/IHC in the determination of ER-positive status in metastatic (mBC) and recurrent breast cancer (rBC) in the United States (US). Methods An Excel-based decision tree, combined with a Markov model, was developed to estimate the economic consequences of adding [ 18 F]FES PET/CT to biopsy/IHC for determining ER-positive status in mBC and rBC over 5 years. Scenario A, where the determination of ER-positive status is carried out solely through biopsy/IHC, was compared to scenario B, where [ 18 F]FES PET/CT is used in addition to biopsy/IHC. Results The proportion of true positive and true negative test results increased by 0.2 to 8.0 percent points in scenario B compared to scenario A, while re-biopsies were reduced by 94% to 100%. Scenario B resulted in cost savings up to 142 million dollars. Conclusions Adding [ 18 F]FES PET/CT to biopsy/IHC may increase the diagnostic accuracy of the ER status, especially when a tumor sample cannot be obtained, or the risk of a biopsy-related complication is high. Therefore, adding [ 18 F]FES PET/CT to biopsy/IHC would have a positive impact on US clinical and economic outcomes.