ESR1 and breast cancer: We have also identified 1294 significantly dysregulated mRNAs in tumor versus normal adjacent breast tissues that can classify the mRNA-based subtype of Lebanese samples as luminal B. Luminal B subtype is the more aggressive type of ER+ breast cancer that is associated with a risk of early relapse because luminal B tumors have higher expression of proliferation/cell cycle-related genes as compared to luminal A tumors9,14.