ESR1 and cancer: Screen-detected cancers are more often smaller tumors that are lymph node negative, estrogen receptor (ER)-positive, and of low grade, compared with interval cancers.14-16 Studies using the prognostic molecular subtypes defined by expression profiling (ie, luminal, HER2-positive, and basal) have shown that screen-detected tumors are more likely to be luminal A subtype and less likely to be basal-like, consistent with improved outcomes.12