Abstract IA50: The epidemic of hepatocellular cancer: A public health and South Texas viewpoint
Authors: Thompson Ian M. 
Published: October 2015

A confluence of events will dramatically change the dimension and face of cancer in the United States over the next several decades. Perhaps most significant, are demographic changes including the growth of adults age 65 or older from 35 million in 2000 to 72 million by 2030. As perhaps the greatest risk factor for neoplastic disease is age, it can be expected that the number of cancer cases will increase accordingly. Concurrent with this nonspecific increase in rate will be a change in the fraction of the US population who are minorities; while the non-minority population is expected to grow slightly between 1980 and 2013, an almost 250% increase in the minority population is expected between 1980 and 2030. The majority of the growth in the US population will be among the Hispanic population.

Around the world, primary liver cancer – hepatocellular cancer (HCC) - is the third largest cause of cancer mortality; in the United States it is the seventh. , As a harbinger of the challenge faced in the US, between 1992-2005, HCC incidence rates in SEER increased from 3.1 to 5.1/100,000 persons and liver cancer mortality increased from 3.3 to 4.0/100,000. While the overall US incidence and mortality rates from HCC are 5.9 and 4.3 per 100,000 population, the rates among Hispanics are 9.5 and 7.0, respectively, 60 and 40% increased risk, respectively. Of all subgroups examined in a recent analysis, the greatest rate of increase in HCC mortality between 2000-2010 were Hispanics 50-64 who experienced a 10.4% increase as compared to an approximately 6% increase among other races/ethnicities of this age range. Overall, HCC is the fastest rising cause of cancer-related death.

The risk and rate of HCC in South Texas is greater than almost any region in the United States. Overall, US Latino males have a risk of HCC of 11.9/100,000 population. This compares with a rate of 14.8/100,000 in Texas Latino males (relative risk 1.24) and 17.3/100,000 in South Texas Latino male (relative risk 1.45). While the rate of HCC in Latino women in South Texas is considerably less (5.4/100,000), the relative risk is increased similarly – 1.42. Of interest, for non-Latino men and women living in South Texas, rates are increased (relative risk 1.24 and 1.30, respectively) albeit not to the same extent.

An unanswered question of major importance is why such extraordinary rates of HCC are found in South Texas as well as why this epidemic disproportionately affects Hispanics. To understand the potential causes of this disparity, a comparison of risk factors for HCC and the rates of these risk factors in South Texas may provide a glimpse into the link. World-wide, the risk factors include infection with hepatitis B or C viruses, excessive alcohol intake, diabetes and the metabolic syndrome, obesity, hepatotoxin exposure such as aflatoxin, nonalcoholic steatohepatitis (NASH), and some metabolic disorders.

In regards to diabetes (and, by extension, metabolic syndrome), Texas ranks 5th in the nation in the age-adjusted rate of diabetes at 11.1/1,000 of population. Of interest, perhaps due to the healthcare infrastructure in the region, long distances for travel, high rates of poverty, lower educational levels, and lower rates of medical insurance, admissions for diabetes-related long-term complications, a likely surrogate for the severity of diabetes, are among the highest in Texas in the 38 counties of the South Texas region. In the case of NASH, a study of prevalence rates from San Antonio found the rate of NASH among Hispanics to be double that of non-Hispanic Caucasians. For obesity, the impact is likely to be substantial. About 27% of Texas adults are estimated to be obese with that rate doubling since 1990. Even of greater concern is that one third of school children in Texas are overweight. In South Texas, the prevalence of obesity among adults is 37.9% as compared to a rate of 24.6% in non-Hispanic whites. Obesity rates for Hispanics in the rest of Texas are 34.2%. Rates of aflatoxin and other exposures in South Texas are currently under study by a team of epidemiologists at the University of Texas Health Science Center at San Antonio leveraging community-based cohort studies in the region. In the South Texas Health Status Review, the reported rate of heavy alcohol use was 5.5%, not significantly higher than that of Texas or the rest of the U.S. The rate of Hepatitis C exposure for this population, as opposed to that of the rest of the U.S. is unknown.

Summary: South Texas has one of the highest rates of hepatocellular cancer in the US; the disease disproportionately affects Hispanic men in this region. Of the etiologies, it would appear that the confluence of diabetes, obesity, and fatty liver disease may be the primary exacerbating factors. Most importantly, these diseases have the potential for control with behavioral therapies.

Citation Format: Ian M. Thompson. The epidemic of hepatocellular cancer: A public health and South Texas viewpoint. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr IA50.