Interrogating HER2 at the mRNA regulation may yield additional insights.32 One of the advantages of an mRNA assay is that results can be reported in continuous variables instead of categorical scoring variables such as in the case with IHC.33 Categorical variables have ceiling effects, have less discrimination between values, and can be subjective depending on the pathologist, particularly in cancers other than breast where standardization is less clear and IHC interpretation is more difficult. This evidence concerns the gene ERBB2 and cancer.