ERBB2 and breast cancer: As the Calgary Tamoxifen Breast Cancer Cohort is not defined by a particular subtype of breast cancer and the different subtypes are known to have distinct biology, we classified patients for which there was corresponding ING1 expression data into luminal breast cancer (ER positive and Her2 negative, n=430) and non-luminal breast cancer (ER negative or Her2 positive, n=32) groups for analysis.