ERBB2 and urinary bladder carcinoma: At the same time, the proportion of HER2-low cases (1+ or 2+ without amplification)—around 35% of all cases—is higher than that in certain previous series of advanced bladder cancer (~17–20% in the literature) [6], but, in our study, additional in situ hybridization was not performed, so some of the 2+ cases may fall into the HER2-positive group.