ESR1 and breast cancer: High SFPR1 expression was significantly associated with lower recurrence-free survival (RFS; HR = 0.68; logrank p = < 0.0001; Figure 8A) and overall survival (OS; HR = 0.59; logrank p = < 0.01; Figure S4A) in ERα-positive breast cancer patients in the KMplot.com gene expression public dataset [27].