A 35-year-old woman, already treated with surgery, chemotherapy, and radiotherapy for a ductal carcinoma of the left breast, underwent an 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) scan for an increase of the serum markers carcinoembryonic antigen (CEA) and cancer antigen 15.3 (CA15.3). This evidence concerns the gene CEACAM5 and breast ductal adenocarcinoma.