Abstract IA003: Trends in cancer mortality in young adults in selected upper-middle and high-income countries with focus on colorectal cancer: an update to 2026.

Abstract An increasing incidence, but also mortality, from colorectal cancer (CRC) in young adults, i. e. in more recent generations, has been reported in several high-income countries over the last decade. We updated trends in cancer mortality in 15 countries (plus the EU) and predicted the number of deaths and rates for 2026, with focus on CRC. We analysed mortality data from the WHO dataset at age 25–49 in the 15 most populous upper-middle and high-income countries providing valid data from 1990 to 2022 or the latest available year – plus the EU. We derived population estimates from the UN World Population Prospects database. We computed age-standardised mortality rates (ASMR, world standard) for all cancers combined and for the most common sites in young adults (colorectum, lung, pancreas and breast). For CRC, we also computed ASMR for the 30–39 age group. We compared the ASMRs around 2020 with those around 2010. We performed a Joinpoint regression on all cancers combined and on the most common sites, over the period 1990-2022. We predicted the number of deaths for 2026 based on a log-linear regression model applied on the most recent segment identified through Poisson Joinpoint regression. Around 2020, the highest overall cancers rates were in Latin America and Eastern Europe (over 35/100, 000 females, 25/100, 000 males), while the lowest ones were in the Republic of Korea, Canada, and Japan (below 20/100, 100 in both sexes). Between 2010 and 2020, all countries showed declines in total cancer mortality (by 10% to above 25% in both sexes), except Mexico and Argentina for females. However, CRC mortality increased appreciably in the UK (by about 30%) and in Northern and most Latin America (by about 10%), though it declined in most Europe, Japan, and the Republic of Korea. When the analysis was restricted to the 30–39 age group, i. e. the generation born in the 1980’s, substantial increases in CRC mortality were observed over the last decade in the UK, North and Latin America, and Australia, and to a lesser extent in Europe and Japan. Mortality tended to decrease for pancreatic and to a greater extent for lung and breast cancer in most countries. Thus, overall cancer mortality in young adults declined in the countries considered. This is mainly due to tobacco control for lung - with substantial declines proportionally similar for both sexes - and pancreatic cancer, as well as for other tobacco-related neoplasms. Improved diagnosis and treatment had a key role on favourable trends of breast cancer and several other neoplasms common in young adults. However, CRC mortality in young adults increased in several, but not all, countries considered. The increase was proportionally greater at age 30-39, i. e. among the generation born in the 1980’s compared to that born in the late 1970’s. The rising CRC mortality rate can be due to the increased prevalence of overweight, obesity, and consequently diabetes, but other (dietary) factors may be involved. This therefore deserves continued attention. Citation Format: Carlo La Vecchia, Silvia Mignozzi, Claudia Santucci. Trends in cancer mortality in young adults in selected upper-middle and high-income countries with focus on colorectal cancer: an update to 2026. abstract. In: Proceedings of the AACR Special Conference in Cancer Research: The Rise in Early-Onset Cancers—Knowledge Gaps and Research Opportunities; 2025 Dec 10-13; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2025;31 (23Suppl): Abstract nr IA003.