ESR1 and breast cancer: IL-6 and IL-8 levels are related to ER and Her-2 antigen expression in patients with ductal carcinomas; ER+ Her2- breast cancer patients are associated with higher serum IL-6 levels than the ER- Her-2+ breast cancer patients; serum IL-6 and IL-8 levels are independent of PR expression in the breast cancer patients15,25.