ERBB2 and breast cancer: Case #17 was a lung metastasis from breast cancer originally classified as ISH group 5 with HER2/CEP17 ratio of 1.25 and average of HER2 copy number of 2.90, classified by IA as ISH group 4 with HER2/CEP17 ratio of 1.63 and average of HER2 copy number of 4.06.