"Liver cancer incidence and mortality have been on the rise in the United States, despite a steady decline in overall cancer incidence and mortality over the past 15 years," said the study's lead author, 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.
‘Individuals of Mexican descent who reside in the US have more risk factors for liver cancer than those who live in Mexico’
"Chronic liver disease, which can lead to liver cancer, is a leading cause of mortality in Mexico and among people of Mexican descent living in the United States. We wanted to compare the prevalence of risk factors in these two groups."
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 that Mexican-American men and women were more likely to be obese (overall and abdominal obesity), diabetic, and heavy drinkers than those born and living in Mexico.
The results were reversed for hepatitis B or C infection. The study showed that Mexican-American men and women were less likely to have hepatitis B or C infections than their counterparts in Mexico.
Flores said it is important for health care practitioners to be aware of the numerous risk factors that may lead to liver disease in their patients of Mexican descent.
"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," she said.
"More studies are needed to evaluate how the accumulation of specific risk factors may be contributing the increased risk of chronic liver disease in Mexican-Americans."
Flores added that other ethnic minority groups, including Asians, other Latinos, and African-Americans, also face liver cancer incidence and mortality rates significantly higher than the rates for non-Hispanic whites, and a deeper understanding of liver cancer risk factors could help inform prevention efforts.
"We need more comprehensive and precise exposure assessment approaches that can improve the prevention, early detection, and treatment of chronic liver disease, in order to delay or prevent the progression to liver cancer," she said.
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.