ESR1 and breast cancer: In a report from the Danish Breast Cancer Cooperative Group, patients with grade III tumors showed a higher proportion of non-classical subtypes and significantly worse prognosis for overall and disease-free survival, in comparison with patients with grade I/II carcinomas.12 In another report, histological grading was correlated with other factors for poor prognosis, such as increasing tumor size, positive lymph nodes, vascular invasion and estrogen receptor negativity.