European Association for the Study of Obesity-Defined Obesity Trajectories and Risk of Incident Cancer Among Middle-Aged and Older Chinese Adults

The European Association for the Study of Obesity (EASO) framework defines obesity by integrating adiposity measures with obesity-related clinical complications. Whether EASO-defined obesity and its longitudinal trajectories are associated with incident cancer remains unclear. This prospective cohort study used data from the China Health and Retirement Longitudinal Study from 2011 through 2020. Associations of baseline EASO-defined obesity and rule-based obesity trajectories with incident cancer were estimated using Cox proportional hazards models. Among 11,951 participants, 2,814 had EASO-defined obesity at baseline and 355 developed incident cancer. In the primary model, baseline EASO-defined obesity was associated with a higher risk of incident cancer (hazard ratio [HR], 1.43; 95% CI, 1.14-1.80). Among 6,448 participants with trajectory data, consistent obesity (HR, 1.83; 95% CI, 1.24-2.69) and fluctuating obesity (HR, 1.97; 95% CI, 1.09-3.55) were also associated with higher cancer risk. EASO-only obesity, defined as EASO-defined obesity without BMI-defined obesity, was associated with higher cancer risk compared with meeting neither obesity definition (HR, 1.41; 95% CI, 1.06-1.87). EASO-defined obesity and persistent or fluctuating obesity trajectories were associated with higher incident cancer risk. The EASO framework identified adults not classified as having obesity by BMI criteria who nevertheless had elevated cancer risk.