Diabetes and racial/ethnic differences in hepatocellular carcinoma risk: the multiethnic cohort.

BACKGROUND Diabetes is an emerging risk factor for hepatocellular carcinoma (HCC), but prospective data from different ethnic populations are scarce. We examined the association between diabetes and HCC in 168679 African Americans, Native Hawaiians, Japanese Americans, Latinos and whites in the Multiethnic Cohort. METHODS During a 15.7-year follow up period, 470 incident HCC cases were identified. Risk factor data were obtained from the baseline questionnaire. Cox regressions were used to calculate hazard rate ratios (RRs) and 95% confidence intervals (CIs) for HCC associated with self-reported diabetes. The population attributable risk percent associated with diabetes was also calculated. All statistical tests were two-sided. RESULTS The RRs for developing HCC (vs whites) were 2.73 (95% CI = 2.00 to 3.72) for Latinos, 2.48 (95% CI = 1.59 to 3.87) for Hawaiians, 2.16 (95% CI = 1.52 to 3.07) for African Americans, and 2.05 (95% CI = 1.50 to 2.81) for Japanese. Diabetes was associated with HCC across ethnic groups (RRLatinos = 3.36 [95% CI = 2.41 to 4.70], RRHawaiians = 2.50 [95% CI = 1.11 to 5.64], RRJapanese = 2.34 [95% CI = 1.60 to 3.41], RRwhites = 2.15 [95% CI = 0.95 to 4.90], and RRAfrican Americans = 2.02 [95% CI = 1.17 to 3.48]). We estimated that 27% of HCC cases in Latinos, 18% in Hawaiians, 13% in African Americans, 12% in Japanese, and 6% in whites were attributed to diabetes. CONCLUSIONS Latinos were at the highest risk of developing HCC, followed by Native Hawaiians, African Americans, Japanese and whites. Diabetes is a risk factor for HCC in all ethnic groups, and eliminating diabetes could potentially reduce HCC incidence in all ethnic groups, with the largest potential for reduction in Latinos.