ESR1 and breast carcinoma: When comparing 2,430 post-MBS patients to 2,430 matched non-surgical females, Hassinger et al. found reduced overall breast cancer incidence (0.7% versus 1.3%, p = 0.03), lower incidence of invasive breast cancer (0.6% versus 1%), and lower incidence of ER+ tumors (36.4% versus 70%, p = 0.04) in the post-bariatric group 75.