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Liver cancer rates vary widely among patients of Asian descent, USC study finds

Breaking down broad ethnic and racial categories into more specific groups can sharpen data, according to a Vietnamese medical student’s research

liver cancer rates
Chronic infection by the hepatitis B and C viruses accounts for many cases of liver cancer, particularly in Southeast Asian populations, according to USC researchers. (Illustration/iStock)

Identifying patients at a greater risk for specific illnesses could be greatly improved by breaking down broad ethnic and racial categories into more specific groups, according to findings in a research paper published by Keck School of Medicine of USC student Christopher Pham.

Pham, a fourth-year student working in the Burn Center at the Los Angeles County+USC Medical Center, is the American-born son of Vietnamese immigrants who settled in the Little Saigon area of Westminster.

Chris Pham cancer researcher

Christopher Pham focused his research on cancer that affected the Vietnamese community at disproportionately higher rates. (USC Photo/Paul Boutin)

“In my community, there are high rates of hepatitis and liver cancer, which hep B and C can cause,” said Pham, who received guidance in his research from two faculty members and analytical assistance from the Department of Preventive Medicine.

But because cancer data categorized a vast cross-section of the population as simply “Asian,” he said, the collected data didn’t call out what Pham personally observed. That, he said, is because the overall prevalence among all Asians is lower, and the data used for research includes far more people from other Asian subgroups not as prone to these diseases.

“Yet the genetics of each group are different, as are the epigenetic markers, cultural habits, social habits and economic situations,” he said. “All of these affect individual risk.”

Liver cancer rates: aggregated data and Asian subgroups

As part of his training in the Keck School of Medicine of USC’s MD program, through the Required Scholarly Project, Pham found mentorship in Lihua Liu, associate professor of clinical preventive medicine, and Tse-Ling Fong, associate professor of medicine, to explore research opportunities addressing his concerns.

Using available data from the Los Angeles Cancer Surveillance Program, Pham’s team analyzed statistics for HCC (hepatocellular carcinoma, a common and often fatal form of liver cancer) from the entire state of California across a 24-year span from 1988 to 2012.

“I looked at some previous studies, and the major ones only used an ‘Asian’ grouping or were for a smaller geographic area, like one in San Francisco.”

Pham’s study was not limited only to what researchers call “aggregated data,” in which patients are lumped into a broad “Asian” bucket, but broken down into subgroups. For the study, the Asian subgroups were Vietnamese, Chinese, Cambodian, Laotian, South Asian, Japanese, Korean and Filipino.

“A lot of the available data simply didn’t have this level of detail,” he said.

The findings backed up his personal observation: Patients of Vietnamese descent did indeed show the highest rate of HCC.

If I were their physician, I would screen anyone from a high-risk area, such as the Southeast Asian countries.

Christopher Pham

“If I were their physician, I would screen anyone from a high-risk area, such as the Southeast Asian countries,” he said.

White House publishes a best-practices guide

While the study was the first to look at liver cancer at its size and detail, a national drive for more fine-grained data — not only on health, but on socioeconomic and other issues — already comes from the top: The White House Initiative on Asian Americans and Pacific Islanders has published a best-practices guide for disaggregating federal data.

“Disaggregated data can help us target resources where they’re most needed,” according to a statement on the initiative’s website.

But collecting and analyzing that data requires funding and prioritization, said Pham, who noted that researchers are pushing for disaggregated data to better understand the different trends of different diseases.

“My idea for the whole project was that if we can separate out the data and prove there are differences, hopefully people who are trying to write grants in the future, or push for community interventions, are able to hone in on specific targets,” he said.

As a clinician, Fong said, he views the study as both confirming physicians’ observations of patients and adding potentially life-saving metrics.

“The risk of HCC among Vietnamese, Cambodians and Laotians is two times higher than Chinese and five times higher than Japanese,” he said. “These findings are important in strategizing liver cancer screening among Asian-Americans.”

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Liver cancer rates vary widely among patients of Asian descent, USC study finds

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