IL6 and breast cancer: IL6 is one of the pro‐inflammatory cytokines which is secreted by various types of cells including cancer cells, and it is involved in regulating proliferation and differentiation of cancer cells, and found to be high in serum or tumor tissues of various cancers, such as breast cancer, prostate cancer, pancreatic cancer, etc. Inhibiting IL6 downstream signal pathway may augment therapeutic efficacy in those cancers with elevated level of IL6.26, 27