Cancers emerging early in adulthood: Analysis of trends and patterns in European cancer registries

Background: Although cancer is typically a disease of the older age groups, some types start emerging early in adulthood. This implies that exposures and stressors occurring before adulthood might play a role in the risk of cancer in adults. Little research has been conducted in this area. Methods: We used European data from the Cancer in Five Continents Vol. XI to calculate cumulative risks by the end of subsequent adulthood decades of age (20–29, 30–39, 40–49) for 34 cancer sites and classified them as early-age emerging cancers if they reached 0.005% by 29 years old, intermediate-age emerging cancers by 39 years old, and late-age emerging cancers after 40 years old. We used data from Cancer in Five Continents Plus to analyse time trends in incidence rates by age groups over the period 1998–2012. Findings: We identified 14 early-age emerging cancers. Nine of them showed significant increasing trends over calendar time in the early decades of adulthood, often more pronouncedly so in 20–29-year-olds than in 30–39 or 40–49-year-olds. The increase of colon cancer rates in the 20–29-year-olds was particularly high with an average annual percent change of 7.9% (95% confidence interval: 5.9%–10%). Decreases in incidence rates were only observed for cancer types classified as intermediate- or late-age emerging cancers. Interpretation: Cancer prevention efforts seem to have favourably impacted intermediate- and late-age emerging cancer incidence rates. For early-age emerging cancers, aetiological research is needed to identify exposures and stressors occurring early in life, especially for those cancers that have been increasing in young adults. This knowledge will be essential to develop preventive strategies.