ESR1 and breast cancer: Abbreviations: BBD (benign breast disease); ctlncRNA (circulating cell-free tumor lncRNA); ctmiRNA (circulating cell-free tumor miRNA); ER+ (estrogen receptor-positive breast cancer); HC (healthy controls); HER2+ (HER2- positive breast cancer); LumA (Luminal A breast cancer); LumB (Luminal B breast cancer); OS (overall survival); PR+ (progesterone receptor-positive breast cancer); TNBC (triple-negative breast cancer).