Negative ER Expression Assessed by 18F-FES PET/CT in the MBC With ER-positive Primary Tumor

Negative Estrogen Receptor (ER) Expression Assessed by 18F-fluoroestradiol Positron Emission Tomography/Computed Tomography (18F-FES PET/CT) in the Metastatic Breast Cancer (MBC) With ER-positive Primary Tumor

To investigate the treatment pattern and efficacy of patients with positive primary ER lesion but negative ER expression in MBC using a novel convenient way of 18F-fluoroestradiol positron emission tomography/computed tomography (18F-FES PET/CT).

Inclusion Criteria:

• Patients diagnosed with breast cancer (according to International Classification of Diseases 10th Revision) with confirmed metastasis, regardless of being de novo diagnosed or progressed from a non-metastatic stage.
• MBC patients who underwent 18F-FES PET/CT at the Fudan University Shanghai Cancer Center between 2010 and 2022
• Patients diagnosed with primary ER-positive tumor and who were yet to receive any systemic therapy during the advanced stage

Exclusion Criteria:

• Patients with incomplete medical records and those diagnosed with secondary primary tumors