Geographic and sociodemographic variations in disease burden, epidemiological trends, and risk factors of early-onset lung cancer: A global analysis.

11169 Background: Exploring the emerging trend of early-onset lung cancer (EOLC) burden is pivotal for guiding the implementation of preventive strategies among young adults. We aimed to provide a comprehensive examination of the geographic and sociodemographic variations in the disease burden, along with epidemiological trends and risk factors associated with EOLC over the past three decades. Methods: EOLC refers to lung cancer diagnosed in individuals aged 20-49 years. Utilizing the GBD 2019 data, we estimated the age-standardised incidence, mortality, and disability-adjusted life years (DALYs) rates for EOLC by sex, socio-demographic index (SDI) quintiles, and geographical location for the period from 1990 to 2019. We investigated the relationships between concomitant risk factors and EOLC incidence at national level, and calculated the DALYs attributable to risk factors. The relative contribution of population growth, population ageing, and epidemiological changes to the variations in burden of EOLC over study period was measured using the decomposition analysis. Incidence was forecast to 2040 using the Bayesian age-period-cohort model. Results: A total of 135,704 EOLC cases, equating to a age-standardised incidence rate of 4.0 (95% UI 3.6 to 4.3) per 100,000, were estimated in 2019 worldwide and was the second leading cause of cancer death among young adults, with higher disease burden occurred in males and those from middle and high-middle SDI regions. An overall decreasing trend in burden of EOLC was observed globally; such trends were more pronounced among males and followed a gradient across SDI levels, with the greater decrease observed in high and high-middle SDI regions. Sex, tobacco smoking prevalence, per capita cigarette-equivalent estimates, average age of smoking initiation, ambient ozone pollution, and GDP per capita were independently and significantly associated with EOLC incidence at the population level. Smoking remained the top contributor to burden of EOLC, with the exception of Andean Latin America, North Africa, and the low SDI regions, where ambient particulate matter pollution and household air pollution from solid fuels ranked as the foremost attributable risk factors. Population growth was the primary driver behind the global increase in EOLC cases in low and low-middle SDI regions, while epidemiological changes accounted for the most substantial reduction in EOLC cases across most regions. The global incidental cases of EOLC was projected to increase by 31.1% in 2040, with a more pronounced increase in females and those from high-middle and middle SDI locations. Conclusions: Our findings underscore significant geographic and sociodemographic disparities in the epidemiological burden of EOLC, emphasizing the necessity for policymakers to devise and apply region-specific, evidence-driven preventive strategies.