ESR1 and endometrial cancer: The risks include a decrease in bone density with an increased fracture risk, an increased risk of thromboembolic events and an increased risk of endometrial cancer.37 Fixation issues, lack of use of tissue controls, diverse immunohistochemical protocols (i.e. different antibodies and antigen retrieval methods) that were probably not validated as recommended by ASCO and CAP, and heterogeneity in interpretation criteria for reporting the results could explain most of the ER and PgR testing discordances between the local and reference laboratories in Brazil.