Examining Liver Cancer Risk Factors

Mexican-Americans face different – and perhaps greater – risks for developing liver cancer than Mexican residents.

Liver cancer is a relatively rare cancer type, but its incidence and mortality have been on the rise in the United States over the past 15 years.

The disease has a well-documented list of risk factors: Hepatitis B or C, obesity, diabetes, and heavy alcohol use. It is also known to affect certain ethnic groups disproportionately, including Asian-Americans, Pacific Islanders, and Mexicans.

Yvonne N. Flores, PhD, associate professor at the UCLA Cancer Prevention and Control Research Center, Fielding School of Public Health and Jonsson Comprehensive Cancer Center, and the UCLA Kaiser Permanente Center for Health Equity, led a recent study comparing liver cancer risk factors for people of Mexican decent living in the United States compared with those living in Mexico.

Flores’s study showed that Mexican-American men and women were more likely to be obese, diabetic, and heavy drinkers than those born and living in Mexico.

The results were reversed for hepatitis B or C infection, with the Mexican population more likely to be infected than the U.S. residents.

"Having a combination of risk factors for liver disease, such as obesity and excessive drinking, or diabetes and chronic hepatitis C infection, has been shown to increase risk of liver cancer," said Flores, who presented her study at the 10th AACR Conference on The Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved. "More studies are needed to evaluate how the accumulation of specific risk factors may be contributing to the increased risk of chronic liver disease in Mexican-Americans."

In this study, Flores and colleagues examined data for Mexican-Americans living in the U.S. from the 1999-2014 National Health and Nutrition Examination Survey; and data from Mexican residents from the Health Worker Cohort Study, conducted from 2004 to 2006, with follow-up conducted from 2011 to 2013. The total study sample included 13,798 individuals—9,485 Mexicans residing in Mexico; 2,324 U.S.-born Mexican-Americans living in the United States; and 1,989 Mexican-Americans who were born in Mexico and now live in the United States.

They evaluated the participants for the primary known risk factors for liver disease, including infection with hepatitis B or C virus, metabolic syndrome, high total cholesterol, diabetes, overall obesity, abdominal obesity, and heavy alcohol use.

After controlling for age, marital status, and education level, the results showed the differences in how risk factors affect the two population groups. Flores said the study results were not surprising, but that they shed a light on the high prevalence of obesity and drinking in the Mexican-American male population.

Flores cautioned that further research would be necessary to determine whether the results of this study are applicable to all Mexicans and Mexican-Americans. She said the study’s primary limitation is that the data from Mexico came from the Health Worker Cohort Study, so the participants may have been younger and more educated than the general public. She said the researchers consulted broader Mexican population studies and found similar overall trends.

The study was funded by grants from the Programa de Investigación en Migración y Salud, the Instituto Mexicano del Seguro Social, and the Consejo Nacional de Ciencia y Tecnologia. The authors declare no conflicts of interest.

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