Early-onset cancer burden and risk: A population-based study

BACKGROUND: The burden of early-onset cancers increases globally, raising major concerns. There is, however, confusion between trends in the number of cases and in age-standardized rates, and a lack of comparison with later-onset cancers. We described trends in cancer burden and risk in early- and later-onset cancers in Switzerland between 1982 and 2021. METHODS: We used data from the Swiss National Institute for Cancer Epidemiology and Registration, including all primary cancers between 1982 and 2021. A cancer was early-onset if diagnosed between ages 20-49 and later-onset at 50 or older. We calculated mean annual number of cases and deaths, crude and age-standardized incidence and mortality rates per 100,000, by 5-year period, sex, and cancer site. We estimated absolute and relative changes between 1982-1986 and 2017-2021. RESULTS: Between 1982 and 2021, the mean annual number of early-onset cancers increased by 1534 (+48%) and of later-onset cancers by 19,832 (+91%). Age-standardized incidence rates of early-onset cancers increased by 13/100,000 (+11%) and of later-onset by 92/100,000 (+8%). Population growth and ageing explained 73% of the increase of early-onset and 90% of the increase of later-onset cancers. The incidence increased in women (early-onset: +19%; later-onset: +9%) but not in men. For main cancer sites, early- and later-onset incidence showed parallel trends, except for colorectal (early-onset increased while later-onset decreased) and for lung in women (early-onset decreased while later-onset increased). All sites together, age-standardized mortality rates declined substantially (early-onset: -59%; later-onset: -38%). CONCLUSIONS: The increase in the burden of early-onset cancers was driven mainly by population growth and ageing, and to a lesser extent by an increased risk, also observed in later-onset cancers.