Striking Rural-Urban Disparities in Liver Cancer in the United States

By Megan Brooks

November 20, 2020

NEW YORK (Reuters Health) - A new study highlights the growing rural-urban disparity in new cases of hepatocellular carcinoma (HCC) in the United States.

HCC is the most common primary cancer of the liver and is currently the fastest growing cancer in the United States, Dr. Christina Gainey of Los Angeles County-USC Medical Center said in a presentation of the data November 16 at The Liver Meeting, held by the American Association for the Study of Liver Diseases.

Since 2009, incidence rates have slowed but only in urban areas. New diagnoses of HCC in rural areas continue to grow, "which has led to a growing disparity gap," she noted.

The research team compared HCC incidence trends in urban and rural areas from 1995 to 2016. They collected and analyzed data on more than 310,000 newly diagnosed cases of HCC.

They found that age-adjusted HCC incidence rates were higher in urban areas versus rural areas (6.9 vs. 4.9 per 100,000). "But it's really the trends over time that tell a different story," Dr. Gainey said.

Before 2009, new HCC cases were rapidly growing in both areas, with rates increasing by around 5.5% each year. But after 2009, the two really started to diverge. The growth in urban cases slowed considerably to around 2.7% per year, while rural cases continued to increase rapidly at a rate of 5.7% per year, "with really no signs of slowing down," Dr. Gainey reported.

Over the 20-year study period, rural non-Hispanic whites and blacks experienced the greatest average annual increase over time. And across all racial-ethnic groups, men were affected more than women. The only racial-ethnic group with an overall decline over 20 years was urban Asian-Pacific Islanders, Dr. Gainey noted.

"Our study really highlights a critical public-health issue that is disproportionately affecting rural Americans who make up a considerable portion of our population - close to 60 million people or one in five Americans," Dr. Gainey said.

It remains unclear why new cases of HCC continue to rise in rural areas, she said.

"Rural residents already face considerable health inequities when it comes to access to care, mortality, and public health infrastructure. They also have higher rates of smoking, obesity and substance-use disorders, all of which can increase the risk for HCC. Disparities have been identified for a number of other cancers, including cervical and colorectal cancer," she noted.

"Our next steps will really be to determine which risk factors are contributing to this disparity so that we can better inform public health strategies and cancer reducing interventions," she concluded.

SOURCE: The Liver Meeting 2020, American Association for the Study of Liver Diseases, presented November 16, 2020.