Interestingly, in BC, it has been reported the presence of both β3-AR mRNA and protein, and it has been studied the correlation with the β3-AR polymorphism Trp64Arg that has shown an increased susceptibility to endometrial cancer and a decreased risk of BC, specifically when associated with the Gln27Glu polymorphism in the β2-AR gene [224,225]. The gene discussed is ADRB3; the disease is endometrial cancer.