[18F]FES PET/CT might also predict treatment efficacy; a phase II trial evaluating the efficacy and safety of adding fulvestrant, an oestrogen receptor antagonist, to NAC in oestrogen receptor-positive/HER2-negative patients with locally advanced breast cancer, found that the SUVmax, SUVmean, and total lesion-oestrogen receptor expression of [18F]FES PET/CT in sensitive patients were significantly higher than those in nonsensitive patients (P < 0.05). The gene discussed is ERBB2; the disease is breast cancer.