ESR1 and invasive breast carcinoma: Other studies have reported that mammographic spiculation is a good independent prognostic factor for screening-detected invasive breast cancer.24,25 These favorable characteristics include ER and PR positivity as well as lower histological grade and Ki67 expression.24,26 Samaržija et al. 8 found that longer and thinner spicules were associated with a low Ki-67 index, whereas shorter and thicker spicules were associated with a higher Ki-67 index.