For FISH, the tumor is negative for HER2 gene amplification if the ratio of HER2 gene signals to chromosome17 signals is <1.8 or HER2 gene copy number is <4.0, equivocal when the ratio is 1.8–2.2 or HER2 gene copy number is 4.0–6.0 and positive if the ratio is >2.2 or HER2 gene copy number is >6.0. Here, ERBB2 is linked to neoplasm.