The increasing trend of obesity is suggested to have contributed to the increasing hepatocellular carcinoma (HCC) incidence rates in the United States. However, no studies have examined whether the association between obesity and HCC differs across racial/ethnic groups. We examined body mass index (BMI) in relation to HCC risk in two large prospective cohort studies: the Multiethnic Cohort (MEC) and the Southern Community Cohort Study (SCCS). Between the two cohorts, a total of 637 incident HCC cases (86 Whites, 165 Blacks, 36 Native Hawaiians, 177 Japanese Americans, and 173 Latinos) were identified. BMI and other known HCC risk factor information were assessed from the baseline questionnaire (MEC: 1993-1996; SCCS: 2002-2009). The association between BMI and HCC incidence was examined using a nested case-control approach with four matched controls per case (MEC: 536 cases/2,131 controls; SCCS: 101 cases/404 controls). Conditional logistic regression, accounting for the matching factors was used to calculate multivariable odds ratios (ORs) and 95% confidence intervals (CI) for incident HCC in relation to BMI (<25, 25-<30, and 30 kg/m2, or per 5 kg/m2) in each racial/ethnic group. Additional covariates such as smoking status, diabetes, and alcohol intake were included in the models. Increasing BMI was associated with an elevated HCC risk in Japanese Americans (OR per 5 kg/m2 increase in BMI=1.69; 95% CI: 1.31, 2.16), Whites (OR=1.34; 95% CI: 0.98, 1.82), Native Hawaiians, (OR=1.23; 95% CI: 0.80, 1.89), and Latinos (OR=1.15; 95% CI: 0.95, 1.40), but not in Blacks in the MEC (OR=0.92; 95% CI: 0.70, 1.22) or in the SCCS (OR =0.93; 95% CI: 0.75, 1.15). The combined OR for Blacks across the two cohorts was 0.93 (95% CI: 0.78, 1.10; P heterogeneity=0.95). The association of BMI with HCC differed significantly across racial/ethnic groups (P heterogeneity=0.003). Our results suggest that the association of obesity, as measured by BMI, with HCC incidence varies across racial/ethnic groups. The null association in Blacks is particularly interesting and warrants further investigation.

Citation Format: Veronica Wendy Setiawan, Loren Lipworth, Lynne R. Wilkens, Loic Le Marchand, William J. Blot, Brian E. Henderson. Racial/ethnic differences in the association of obesity with hepatocellular carcinoma risk. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr B28.