HER2-Positive Breast Cancer: Tumor-to-Liver SUV Ratio is the Best Parameter for Detection in F-18 FDG-PET/CT

Fluorine-18 fluorodeoxyglucose (F-18 FDG)-positron emission tomography/computed tomography (PET/CT) is widely used in most malignancy workups, including detection, differential diagnosis, staging and/or restaging, therapeutic decision-making, follow-up, and prognosis.
The aim of this study was to evaluate the usefulness of F-18 FDG-PET/CT for predicting breast cancer molecular subtypes.
Patients and Sixty-six patients with pathologically proven invasive breast carcinoma (IBC) underwent F-18 FDG-PET/CT imaging for tumor staging. The maximum standardized uptake value (tumor SUVmax) of the IBC and mean SUVs of the liver and spleen (liver and spleen SUVmean) were measured. Molecular subtype was determined according to genomic analysis. The tumor SUVmax, tumor-to-liver SUV ratio, and tumor-to-spleen SUV ratio were correlated with molecular subtype data.
Logistic analysis demonstrated that only the tumor-to-liver SUV ratio was a significant parameter for human epidermal growth factor type 2 (HER2)-positive subtype identification (P = 0.0049). The sensitivity, specificity, and area under the receiver-operating-characteristic curve (AUC) of this parameter for HER2-positive subtype detection were 83%, 79%, and 0.87, respectively.
The tumor-to-liver SUV ratio appears to be useful for HER2-positive subtype identification, thus indicating the potential use of F-18 FDG-PET/CT as an imaging biomarker that could facilitate the clinical management of patients with breast cancer.