Researchers from the Wellcome Sanger Institute, University of Cambridge, and Cambridge University Hospitals have uncovered novel DNA mutational signatures induced by various chemotherapy agents in normal blood cells. This study, spanning 21 chemotherapy drugs across multiple classes, reveals differential mutagenic effects of agents such as platinum compounds, with some causing extensive DNA damage and others less so. The findings provide an unprecedented genomic perspective on the long-term side effects of chemotherapy, offering pathways to optimize treatment selection to minimize harm to healthy tissues and potentially reduce secondary cancer risks.