ERBB2 and breast cancer: In a study of molecular subtypes within breast cancer, immunohistochemical (IHC) staining for Ki67 was combined with profiling for human epidermal growth factor 2 (HER2) and oestrogen receptor (ER) demonstrating a higher rate of bone metastasis (87.8%) within ER-positive HER2 negative tumours with a Ki67 score > 13% compared to other subtypes [104].