These studies of both random and systematic variability of global gene expression in the context of presurgical study of breast cancer have revealed modest differences in most genes/pathways but confirmed substantial changes in the expression of early-response genes that appear to be due to ischaemia after surgery and in IL6, IGFB2 and MYC that appear to be responses to initial core-cut biopsy. The gene discussed is IL6; the disease is breast carcinoma.