Associations of anthropometric indices with all-cause and cause-specific mortality among US adults with a self-reported history of cancer: a population-based cohort study

Background Obesity is a well-established risk factor for cancer incidence and mortality. Body mass index (BMI) does not adequately characterize body shape or fat distribution. Whether a body shape index (ABSI) and body roundness index (BRI) are associated with mortality among adults with a history of cancer remains uncertain. Methods We analyzed 3,230 NHANES participants (2003–2018) using survey-weighted Cox models adjusted for sociodemographic, behavioral, and cancer-related factors. Nonlinear and sensitivity analyses were performed. Results During a survey-weighted median potential follow-up of 7.9 years, 937 all-cause, 315 cancer, and 197 CVD deaths occurred. In the primary model, each 1-SD higher ABSI was associated with all-cause mortality (HR 1.24, 95% CI 1.11–1.38) and CVD mortality (HR 1.55, 95% CI 1.26–1.90), but not cancer mortality (HR 1.12, 95% CI 0.96–1.29). Continuous BRI and BMI were not independently associated with the outcomes. Underweight BMI was associated with higher all-cause mortality (HR 2.44, 95% CI 1.46–4.08). BMI had a nonlinear association with all-cause mortality (P for nonlinearity = 0.002). ABSI findings remained similar across sensitivity analyses. Conclusion Higher ABSI was associated with higher all-cause and CVD mortality among U.S. adults with a self-reported history of cancer. Further studies are needed to confirm these associations. Clinical trial number Not applicable.