Specifically, we excluded those records that were inaccessible (n = 8), unsuitable patient populations [i.e., non-HR+ breast cancer (n= 9), non-RCT (n = 378), non-breast cancer (n = 179), early breast cancer (n = 150), and HER2-positive breast cancer (n = 24)], lacked appropriate interventions [non-de novo CDK4/6 inhibitors (n = 32) and non vs. placebo (n = 132)], or lacked survival outcomes (n = 13). This evidence concerns the gene CDK4 and breast cancer.