Diagnosis: Left breast cancer, 1.2 cmHistology: moderately differentiated, ductal invasive, Elston-Ellis grade II, estrogen receptor positive, progesterone receptor pos, S-phase impossible to calculate, 2 of 18 axillary lymphnodes positive, no extranodal growth, benign ovariesTNM-classification: pT1 pN1 pM0. This evidence concerns the gene ESR1 and breast cancer.