In line with data from epidemiological studies suggesting that use of combined MHT and alcohol consumption are associated with elevated risk of hormone receptor-positive (ER + , mostly low grade) but not receptor-negative (ER-, mostly high grade) breast cancers [43, 63–69], our observed associations of combined MHT use and alcohol consumption with breast tissue composition metrics may provide further clues into the role of variations in exposure-tissue interactions in the etiopathogenesis of breast cancer subtypes. The gene discussed is NR4A1; the disease is breast cancer.