Obesity and Cancer Risk in White and Black Adults: A Prospective Cohort Study.

Objective: Anthropometric measures of obesity, including BMI and waist circumference (WC), do not quantify excess adiposity and metabolic abnormalities consistently across racial populations. This study tested the hypothesis that participant race modifies the association of anthropometric measures of obesity and cancer risk.

Methods: This prospective cohort (The Pennington Center Longitudinal Study) included 18,296 adults, 6,405 (35.0%) male sex and 6,273 (34.3%) Black race. The primary exposures were BMI (weight in kilograms/height in meters squared) and WC (centimeters). The primary end point was the time from study enrollment to diagnosis of histologically confirmed invasive cancer.

Results: During a median follow-up of 14.0 years (interquartile range: 9.8-19.0 years), invasive cancer occurred in 1,350 participants. Among men, race modified the association of BMI (P = 0.02) and WC (P = 0.01) with cancer incidence; compared with a BMI of 22 kg/m , a BMI of 35 kg/m in White men was associated with a hazard ratio of 1.83 (95% CI: 1.58-2.12), whereas in Black men, the hazard ratio was 0.89 (95% CI: 0.72-1.11). Among women, race did not modify the association of BMI (P = 0.41) or WC (P = 0.36) with cancer incidence.

Conclusions: In this diverse cohort of adults, participant race and sex modified the prognostic associations of anthropometric measures of obesity and cancer risk.