Association Between Body Roundness Index and Cancer Risk, With Further Stratification by Cardiometabolic Disease Status: Findings From Three National Longitudinal Cohorts.

OBJECTIVE: This study investigates the association between body roundness index (BRI) and overall cancer incidence in a large population-based cohort and explores the consistency of this association in individuals with and without cardiometabolic disease (CMD).

DESIGN: A prospective cohort study.

SETTING: Data for this study was extracted from three cohorts: the English Longitudinal Study of Aging, the Health and Retirement Study, and the China Health and Retirement Longitudinal Study.

PARTICIPANTS: Among 33,624 individuals aged 50 and older, 2999 reported a cancer diagnosis.

MEASUREMENTS: BRI was calculated using measured height and waist circumference, while cancer and CMD were based on self-reported physician diagnoses. Restricted cubic spline curves assessed nonlinearity and identified BRI cutoff points. Cox proportional hazards models were used to evaluate the association between BRI and cancer incidence, with subgroup and interaction analyses conducted by CMD status.

RESULTS: A non-linear relationship was identified between BRI and cancer incidence, with an inflection point at BRI = 5.06. Participants with BRI > 5.06 had a 10% higher risk of cancer (HR: 1.10; 95% CI: 1.02-1.19) compared to those with BRI ≤ 5.06, while increases in BRI below this threshold were not significantly associated with risk. This remained consistent across CMD-stratified analyses. No significant interaction was detected between BRI and CMD status.

CONCLUSION: BRI is associated with cancer risk in a non-linear manner, with increased risk above a defined threshold, irrespective of CMD status. These findings highlight the potential of BRI as a simple tool for cancer risk screening in older adults.