ESR1 and neoplasm: The proportions of SASH1-high and –low cases were similar in ER+ subgroups with high or low proliferative activity (p = ns; data not shown), but stratification of outcome was restricted to ER+ tumours with low proliferative activity (low levels of Ki67, low mitotic score or low histological grade; Figures 6B (i–iv)) and those co-expressing progesterone receptor (Figure 6B (v)).