Sex- and site-specific trends in cancer incidence and survival among adolescents and young adults in Taiwan, 2003-2020.
BACKGROUND Cancer patterns among adolescents and young adults (AYAs; 15-39 years) differ markedly from those observed in pediatric and older populations; however, long-term epidemiological data from Asian populations remain limited. The primary purpose of this study was to characterize temporal and site-specific trends in AYA cancer incidence and survival in Taiwan over an 18-year period. METHODS Using the Taiwan Cancer Registry, all malignancies diagnosed in individuals aged 15-39 years between 2003 and 2020 were analyzed. Cancer sites were classified according to the AYA Site Recode 2020 Revision. Age-standardized incidence rates (ASRs) were calculated using the WHO 2000 standard population, and temporal trends were assessed using joinpoint regression to estimate annual percent change (APC) and average annual percent change (AAPC). Five-year overall survival was estimated using the complete analysis approach. RESULTS Among 107,063 AYA cancers (ASR 62.0 per 100,000), carcinomas predominated (ASR 44.8), with breast, gastrointestinal, and thyroid malignancies accounting for the largest proportions. Overall incidence increased over the study period (AAPC = 1.47%; 95% CI = 1.231.71), mainly reflecting rising rates of breast, thyroid, and lung carcinomas in females. Incidence among males remained stable, with declines in head-and-neck and liver/intrahepatic bile duct carcinomas offset by increases in thyroid and lung malignancies. Five-year overall survival improved from 67.5% in 2003-2005 to 82.1% in 2016-2020, with improvements observed in most major diagnostic categories. CONCLUSIONS AYA cancer incidence and survival in Taiwan changed substantially over two decades, with marked sex- and site-specific heterogeneity. These findings provide population-based evidence to inform cancer control and resource planning in Asian settings.