The Chernobyl accident exposed people located hundreds of kilometres away to fallout, but
increases in cancer incidence as a result of the accident seem, at present, to be restricted to
one tumour type. These thyroid tumours form the largest number of cancers of one type,
caused by a single event on one date, ever recorded. Epidemiological, pathological and
molecular studies have provided new insights into the carcinogenic process, as well as
lessons for future nuclear accidents.