In breast cancer, targeted therapies such as trastuzumab deruxtecan, immune checkpoint inhibitors, everolimus, CDK4/6i, and PARP inhibitors are frequently implicated, while chemotherapeutics (e.g., bleomycin, platinum agents, methotrexate, taxanes, gemcitabine) are common culprits in broader oncology populations (32, 33). This evidence concerns the gene CDK4 and breast carcinoma.