The main research objective was to analyze ERBB2 protein expression comparatively according to the recommendations of the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) for ERBB2/HER2 testing in BC [29] and gastroesophageal adenocarcinoma [30] followed by fluorescence in situ hybridization (FISH) for ERBB2 gain or amplification in UTUCs. Here, ERBB2 is linked to breast cancer.