Diabetes and Liver Cancer Risk—A Stronger Effect in Whites than Blacks?

Both diabetes and liver and biliary tract cancer are overrepresented among African Americans, but limited information is available on the interrelationship of these two diseases among African Americans. We tested the relationship of diabetes with the incidence of liver cancer and whether this relationship varied between blacks and whites. Using the Southern Community Cohort Study, we conducted a cancer follow-up (2002-2015) of a cohort of mostly low income black and white participants aged 40-79 with (n=17,644) and without diabetes (n=64,870) at cohort entry. Mean age and diabetes duration of those with diabetes was 55.0 and 9.5 years, respectively. Mean age of those without diabetes was 51.6 years. Logistic regression was used to compute ORs (95% CIs) for the risk of incident liver and biliary tract cancer. There were 429 incident cases of these cancers. In univariate analyses, diabetes was associated with an increased risk of liver and biliary tract cancer (OR=1.73, 95% CI=1.36-2.21). Upon further controlling for age, sex, race, BMI, current and former smoking, total alcohol consumption, and any hepatitis infection, diabetes remained a significant risk factor for liver and biliary tract cancer (OR=1.49, 95% CI= 1.18-1.89). However, when stratified by race, risk associated with diabetes was significantly greater among whites (OR = 2.67, 95% CI = 1.71-4.19) than blacks (OR= 1.28, 0.98-1.68) (p_interaction=.002). Furthermore, controlling for diabetes greatly attenuated the higher risk of liver and biliary tract cancer among blacks; indeed, while the cancer risk among those without diabetes was twice as high among blacks than whites (OR=2.01, 95% CI = 1.50-2.69), no racial disparity was observed among those with diabetes (OR = 0.95, 95% CI= 0.62-1.45). The findings raise the possibility of markedly different impacts of diabetes on hepatic carcinogenesis between blacks and whites.