Newswise — ALEXANDRIA, VA – Data from a new study presented this week at The Liver Meeting Digital Experience® – held by the American Association for the Study of Liver Diseases – found that the rate of new hepatocellular carcinoma (HCC) cases has slowed since 2009, but only in urban areas. Rural non-Hispanic whites and Blacks have experienced the greatest increases over time when comparing rural and urban HCC trends by specific demographic factors.
Incidence of HCC ─ the most common type of liver cancer─ continues to rise in the United States, but cases have plateaued in recent years. Researchers in California wanted to find out if incidence trends in rural areas, which have notable disparities for other types of cancer, are similar to trends in urban locales. For this new study, they compared HCC incidence trends over a 20-year period to better understand these health disparities between rural and urban areas.
“Rural Americans face considerable disadvantages when it comes to health access and outcomes. Those that live in rural areas also have higher rates of smoking, excessive drinking, obesity and lower levels of physical activity, all of which can increase the risk for HCC,” says the study’s co-author, Christina Gainey, MD, a third-year internal medicine resident at Los Angeles County-USC Medical Center in Los Angeles. “As nearly one in five Americans lives in a rural area, health disparities in this population represent a critical public health issue.”
For the study, the researchers calculated age-adjusted HCC incidence rates (AAIR) using the North American Association of Central Cancer Registries dataset, which covers 93 percent of the United States. They defined “rural” as open countryside with town populations fewer than 2,500 people. ─ “Urban”─ areas were defined as populations ranging from 2,500 to 49,999, but not part of a larger labor market area─ by using the 2013 USDA Rural-Urban Continuum Codes. They made rural versus urban comparisons by sex, race/ethnicity and region then calculated average annual percentage changes and analyzed trends for 1995-2016.
They identified 310,635 HCC cases for the study, including 85 percent urban and 15 percent rural. They found that AAIRs were lower in rural areas compared to urban areas, but the average annual percentage change was higher in rural areas compared to urban locales. In 2009, the rise in urban HCC incidence slowed. There was an average annual increase of +5.3 percent prior to 2009, but only an average increase of +2.7percent from 2009-2016. They did not find any corresponding slowing of HCC incidence rates in any of the rural areas in the study, even after subgroup analysis.
According to the study, rural non-Hispanic whites had the highest incidence increase over 20 years. Urban non-Hispanic Blacks had the highest single segment growth in incidence between 1999-2009, but has slowed since. Rates in rural non-Hispanic Blacks continued to rise during the study period. Urban Asians/Pacific Islanders were the only racial/ethnic group in the study with an overall incidence decline. By 2012, the AAIR in rural Hispanics surpassed that of urban Asians/Pacific Islanders. By 2016, rural Hispanics had the highest AAIR of all the racial/ethnic groups in the study.
“Our study is the first to show that new cases of HCC are disproportionately affecting individuals living in rural America,” says Dr. Gainey. “It is imperative for us to focus our efforts in this vulnerable population to slow the rapid rise in new cases. Our next steps will be to study the drivers of these health disparities to better inform cancer-reducing interventions.”
Dr. Gainey will present these findings at The Liver Meeting Digital Experience ™ during Parallel: Hepatobiliary Neoplasia: Clinical on November 16 at 9 AM ET. The corresponding abstract “Striking Rural-Urban Disparities in Hepatocellular Carcinoma Trends in the United States, 1995-2016” can be found in the journal, HEPATOLOGY.
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