ERα expression and function are linked to a more aggressive phenotype,19whereas ERβ inhibits migration and proliferation,20and expression is linked to less aggressive phenotypes with improved survival.21In support of this, loss of ERβ is associated with a more aggressive cancer phenotype.22A similar association of ERα-“progressive” and ERβ-“suppressive” phenotypes is also seen in other cancers such as prostate cancer.23 This evidence concerns the gene ESR1 and cancer.