Although we have not found an increasing level of E2 in the serum of populations with endometriosis [57], we have detected a local increase in estrogen in breast cancer and endometrial cancer tissue [58, 59]; as an inflammatory condition, endometriosis may promote the accumulation of E2 in local tissue through the action of a series of inflammatory factors such as IL-1, IL-6, IL-8, PGE, etc., and the exact mechanism is worthy of further exploration. Here, IL6 is linked to breast cancer.