A comparison of the evaluation schemes with the ERBB2 amplification status determined by FISH as the gold standard resulted in the following quality features: ERBB2 immunoscoring according to the ASCO/CAP 2018 guidelines for ERBB2/HER2-testing in BC detected 4 true-positive, 111 true-negative, 9 false-positive, and 10 false-negative UTUCs (sensitivity = 30.8%, specificity = 91.7%, positive predictive value = 28.6%, negative predictive value = 92.5%). Here, ERBB2 is linked to breast cancer.