Consequently, discordance between IHC-ISH and NGS was observed in 23.9% (22/92) of cases, which can be attributed to intratumoral heterogeneity (Figure 2A), tumor cellularity, a small number of amplified cells, and a HER2/CEP17 ratio close to the cut-off (Table 4). The gene discussed is ERBB2; the disease is neoplasm.