Notably, the set cut-off value of 3.0 for ddPCR is different from a cut-off defined in the 2018 ASCO/CAP guidelines for ISH analyses, where a tumor is defined positive with a HER2/CEP17 ratio above 2.0, provided the mean HER2 copy number is above 4 per diploid genome. Here, ERBB2 is linked to neoplasm.