ESR1 and breast cancer: In a recent work, we observed a reduced frequency of SARS-CoV-2 infections in hormonal-driven breast cancer patients undergoing SERM (Selective Estrogen Receptor Modulator) therapy (specifically Tamoxifen, Toremifen, or Fulvestrant) compared to treatments inhibiting estrogen synthesis (like Aromatase inhibitors and Luteinizing-hormone-releasing hormone agonists) [16].