ERBB2 and neoplasm: Tumors that do not show any degree of membrane staining are classified as 0+, whereas tumors that either present incomplete staining in >10% of tumor cells (score 1+) or a weak-to-moderate complete membrane staining in >10% of tumor cells (score 2+) but with a negative ISH result, are given a higher IHC score but are still defined as HER2-negative cases [9].