In breast cancer patients, its efficacy in evaluating chemotherapeutic effects has been reported: a correlation was observed between the intensity of FDG uptake and tumor characteristics such as tumor grade, HR status, and HER-2 status [14–16] and the early metabolic response after one or two courses of NAC was shown to predict pCR, particularly for aggressive subtypes [17, 18]. This evidence concerns the gene ERBB2 and breast cancer.