In collaboration with Dr. Stephen Chanock’s team at NCI, we created a comprehensive genomic landscape of papillary thyroid cancers (PTCs) that arose as a consequence of the 1986 Chernobyl nuclear accident (Morton, Karyadi, Stewart, Bogdanova, Dawson, Steinberg, et al., Science 2021). We found radiation dose–dependent enrichment of gene-fusion drivers and structural alterations in the DNA that bore hallmarks of repair pathways. Overall, the data suggest that exposure-related double-stranded breaks in the DNA were an early carcinogenic event, enabling PTC growth later in life.