A previous study has showed that baseline 18F-FDG HI could be used to predict the survival rate of patients with advanced nasopharyngeal carcinoma (29) and that the HI derived from 18F-fluoroestradiol (18F-FES) PET/CT could reflect the estrogen receptor (ER) expression in breast cancer patients (30). The gene discussed is ESR1; the disease is breast carcinoma.