Abstract Colorectal cancer incidence rates vary geographically and have changed over time1 . Notably, in the past two decades, the incidence of early-onset colorectal cancer , affecting individuals under the age of 50 years, has doubled in many countries2-5. The reasons for this increase are unknown . Here, we investigate whether mutational processes contribute to geographic and age-related differences by examining 981 colorectal cancer genomes from 11 countries . No major differences were found in microsatellite unstable cancers, but variations in mutation burden and signatures were observed in the 802 microsatellite-stable cases. Multiple signatures, most with unknown etiologies , exhibited varying prevalence in Argentina, Brazil, Colombia, Russia , and Thailand , indicating geographically diverse levels of mutagenic exposure. Signatures SBS88 and ID18, caused by the bacteria-produced mutagen colibactin 6,7, had higher mutation loads in countries with higher colorectal cancer inciden...
Media Monitoring for Signals about Emerging Threats