Unwelcome Natural Experiments: Cancer Etiologic Insights from Disaster-Exposed Populations.

Enough time has now elapsed to examine the long-term cancer burden among survivors of the terrorist attacks on the World Trade Center on September 11, 2001. In the June 8, 2026, issue of Cancer Epidemiology, Biomarkers, and Prevention, Turner and colleagues reported a 1.8-fold higher cancer risk among 4,815 male World Trade Center responders compared with age-matched controls, with those of 20 to 44 years at the time of attacks at the highest cancer risk. This finding is one of several "unwelcome natural experiments" in which catastrophic disasters have unintentionally advanced cancer epidemiology. Here, we summarize insights gained from other catastrophes: the radiation-related disasters that struck Hiroshima and Nagasaki, Chernobyl, and Fukushima, the industrial-related disasters at Seveso and Bhopal, and the war-related disasters at the World Trade Center and in Vietnam with use of Agent Orange. Each event led to the creation of epidemiologic investigations that have clarified organ specificity, dose-response, and age-at-exposure associations and clarified the long latency for cancer risk associated with diverse exposures. We argue that epidemiologists have a responsibility to ensure such catastrophic events are not in vain; sustained investment in long-term follow-up, biospecimen collection, and disaster-response cohorts are essential to fully understand and mitigate the cancer consequences of catastrophic events. See related article by Turner et al., p. 1709.