Comparative study of early onset cancer burden between China and the United States from 1990 to 2021

China and the United States face a mounting burden associated with early-onset cancers. Comparing the burden and trends of early-onset cancers between the two countries, analyzing attributable risk factors, drawing on the successful experience of the US in cancer research, prevention, and care can provide valuable insights to inform China's prevention and control strategies. A comparative study based on the 2021 Global Burden of Disease repository was conducted to assess the average annual percentage change in the burden of early-onset cancers. Linear regression analysis was performed using the JoinPoint model. The metrics analyzed included the incidence, mortality, disability-adjusted life years (DALYs), and attributable risk factors related to early-onset cancers. In 2021, the number of new early-onset cancer cases was 750,600 in China and 472,600 in the US, with deaths totaling 240,800 and 30,600, respectively. The age-standardized incidence rate (ASIR) in the US was higher than in China, while its age-standardized mortality rate (ASMR) and DALYs were lower. The ASMR declined annually by 1.57% in China and 1.65% in the US, and the age-standardized DALYs rate decreased by 1.50% and 1.71% per year, respectively. Breast cancer, non-melanoma skin cancer, and colorectal cancer were the cancer with the highest ASIR in both countries. Smoking, high fasting plasma glucose, and dietary risks were primary contributors to DALYs losses across various early-onset cancers. Both nations need to adopt preventive and control strategies tailored to young populations, guided by the burden trends of early-onset cancers, to mitigate their social and economic consequences.