One study has identified that ERβ2 regulates immune function in fish macrophages.[177] The immune regulatory roles of ERβ3‐5 remain unclear, although some studies have identified their functions in cancer occurrence and progression.[178] Thus, we strongly advocate that future research should focus on elucidating the roles of different ER subtypes in various cell types during both normal and cancer development. This evidence concerns the gene ESR1 and cancer.