Breast cancer risks for female first-degree relatives were increased if the index cases' tumours: were circumscribed; had pushing margins >50%; had intense lymphocytic infiltrate II; had number of mitoses >50; had a trabecular growth pattern; had extensive intraductal carcinoma; had a syncytial pattern; did not have extensive sclerosis; did not have a glandular growth pattern; or were ER or PR negative (all P <0.04). This evidence concerns the gene ESR1 and breast cancer.