ERBB2 and neoplasm: Moreover, in addition to molecular profiling, it is crucial to systematically investigate the microsatellite instability/mismatch repair deficiency (MSI/dMMR) status of the tumor through immunohistochemistry (IHC) and/or polymerase chain reaction (PCR) testing, taking into account the potential benefits of immunotherapy and the possibility of human epidermal growth factor receptor 2 (HER2) overexpression/amplification, which can be assessed through IHC and/or in situ hybridization (ISH).