Although some cancers are falling for rural US residents, liver cancer is on the rise, a new study has found.
A recent study found that the incidence of hepatocellular carcinoma (HCC) is slowing in urban areas but rising in rural ones.
The study, from the USC Norris Comprehensive Cancer Center, part of Keck Medicine of USC, found that the incidence of the cancer is rising at a rate of 5.7% annually in rural areas and approaching the rates seen in urban areas.
The rural subgroups experiencing a rapid rise in HCC included men ages 60-69, non-Hispanic Blacks, American Indian/Alaskan Natives and those who live in either the Southern part of the country or in a high-poverty area.
The study examined data from 1995-2016.
The researchers also discovered that certain urban subgroups experienced declining incidence rates of HCC starting in 2013, including both men and women, younger individuals ages 40-59, Asian Pacific Islanders, and people who live in the Western United States.
No rural subgroups experienced a clear decline, even as rates of other cancers for those populations are falling, including lung, breast, and colorectal cancer
“Considering that one in five Americans live in a rural community, this study suggests that HCC is a critical underrecognized public health issue affecting rural Americans,” Kali Zhou, MD, MAS, a gastroenterologist and hepatologist with Keck Medicine and co-lead author of the study, said in a statement. She is also an associate member of USC Norris and an assistant professor of Clinical Medicine at the Keck School of Medicine.
HCC is the most common form of liver cancer and the fastest-growing cause of cancer-related deaths in the United States. Historically, the rates of HCC have been lower in rural areas than urban.
The study examined HCC trends across rural and urban communities over the past 20 years for which data is available using the North American Association of Central Cancer Registries database, which covers 93% of the United States and well-represents the rural parts of the country.
Of the more than 310,000 new cases of HCC, 85% were diagnosed in urban and 15% in rural areas. The researchers tracked new cases per year for both geographic groups to discover that while over the entire 20 years, the average rate of new cases was still lower in rural areas compared to urban ones, cases increased at a higher average percentage rate per year in rural areas.
The rates of increase were similar for the 2 groups from 1995-2009. But in 2009, the pace of new HCC cases in urban America began to slow down with a peak around 2014, with no corresponding slowing in rural America.
By 2016, this meant the number of cases increased 218% from 1995 in rural settings, compared with 118% in urban ones.
The study did not examine the reasons for the rise in new HCC cases in rural areas, but Zhou pointed to the prevalence of obesity and alcohol use in those areas as one possible explanation.
In addition, rural residents may lack the same health care access available to city residents as well as preventive cancer care.
Zhou’s previous research showed that people living in rural parts of the country are also more likely to have a late-stage liver cancer diagnosis and worse survival rates than those in urban communities.