Myalgia rate ranged from 5.98 to 20.2% in patients treated with CDK4/6 inhibitors plus ET for early breast cancer which was comparable to myalgia rates reported in the control arms (MonarchE: 5.98% vs. 5.92%; PENELOPE-B: 20.2% vs. 18.5%). This evidence concerns the gene CDK4 and Myalgia.