ERBB2 and cancer: The updated algorithm of the ASCO/CAP guideline for Her2 assessment consists of first-line assessment of Her2 levels with IHC to classify the cancer specimens into four categories: 0/1+/2+/3+ or IHC 0/IHC 1+/IHC 2+/IHC 3+, with 0/1+ being Her2 negative (Her2−) and 3+ being Her2 positive (Her2+).