Burden of primary liver cancer and underlying etiologies among young adults from 1990 to 2021 and modelled Projection to 2050.

This study analyzes the global burden of primary liver cancer among young adults (15-49 years) from 1990 to 2021, revealing a 46.0% rise in incidence and 59.0% increase in prevalence, yet declining age-standardized mortality (Estimated Annual Percentage Change-EAPC = -1.27). Middle-SDI regions faced the highest burden, with East Asia accounting for 66,472 prevalent cases and stark national disparities (e.g., Mongolia ASR = 1846.83/100,000 vs. Morocco ASR = 16.73). Population growth drove 42.8-47.8% of case increases, while metabolic risks and alcohol use (surpassing smoking in 2021) emerged as dominant factors. Males showed a 3.5-fold higher smoking-related risk than females. Deaths rose notably among those ≥30 years, with a 20.6% increase in 30-34-year-olds, signaling earlier onset. A shift from hepatitis B to metabolic/behavioral risks underscores evolving etiology. Projections suggest 133,561 cases by 2050, urging prioritized early screening and equitable resource allocation beyond traditional viral hepatitis frameworks.