WASHINGTON – A combination of risk factors may be driving a large increase in liver cancer among Latinos in the United States, researchers said at a conference sponsored by the American Association for Cancer Research.
Although liver cancer, or hepatocellular carcinoma (HCC), is most common in Asia and Africa, the incidence is on the rise in the United States, primarily due to hepatitis C virus infection. There are 20,000 new HCC cases in this country each year, and liver cancer is the fifth most common cancer in men and the seventh most common in women, according to a recent review article in the New England Journal of Medicine (2011;365:1118-27).
The main risk factors for HCC in Africa and Asia have been infection with hepatitis B or hepatitis C, and alcoholic liver disease. More recently, evidence has suggested that fatty liver disease and metabolic syndrome may be significant risk factors in Western countries, according to the NEJM review.
In the United States, HCC incidence was 1.7 cases per 100,000 in 1980, but by 2005, this figure had increased to 5 per 100,000, noted the lead author of the Texas study, Amelie Ramirez, Dr.P.H., who presented the data at the conference. Dr. Ramirez, director of the Institute for Health Promotion Research at the University of Texas Health Science Center at San Antonio, and her colleagues decided to see if they could tease out some risk factors for HCC and thereby help to explain the increase among Latinos living in that state.
The investigators used data from the U.S. Surveillance, Epidemiology, and End Results (SEER) program, the Texas Cancer Registry, and the Texas Department of State Health Services. They examined the time period 1995-2006 and calculated age-adjusted and age-specific HCC incidence rates as well as the prevalence of obesity, diabetes, heavy alcohol use, and smoking.
Dr. Ramirez and her colleagues found that Latinos accounted for one third of HCC cases in Texas, and about 75% of cases in South Texas. The rates were 10.6 cases per 100,000 in South Texas and 9.7 per 100,000 in the state, compared with 7.5 per 100,000 among Latinos nationally in the SEER database. About 70% of cases were in men, an observation that held across all three populations – SEER, Texas, and South Texas.
Latinos are the fastest-growing U.S. minority group, accounting for 20% of the total U.S. population and 36% of the population of Texas; by the year 2030, Latinos will constitute a majority of Texas’ census, Dr. Ramirez noted (U.S. Census Bureau, 2010). This pattern is especially pronounced in South Texas, a large region that is currently almost 70% Latino.
The researchers also documented increases in the prevalence of obesity and diabetes among Texas and South Texas Latinos. When they analyzed the time periods 1995-1997 and 2004-2006 separately, the researchers found that obesity for all Latinos increased. During 2004-2006, Texas and South Texas Latinos had higher rates of obesity than U.S. Latinos overall. For U.S. Latinos, the obesity rate was 27%, compared with 30% for Texas Latinos and 35% for South Texas Latinos.
Diabetes prevalence also increased among U.S. Latinos overall, while the prevalence figures for South Texas and Texas Latinos showed increases, but they were not significant.
Heavy alcohol use and smoking did not appear to be significant risk factors for HCC in the analyses. However, the study shows that obesity and diabetes, both of which are preventable and treatable, should receive more attention in the Latino population, especially in Texas, Dr. Ramirez said.