Questions for Lead Author Jiaquan Xu, M.D., Epidemiologist, and Author of “Trends in Liver Cancer Mortality Among Adults Aged 25 and Over in the United States, 2000-2016”
Q: What made you decide to focus on liver cancer deaths for this study?
JX: It was the dramatic rise in the death rate for liver cancer that caused me to want to look more deeply into various aspects of this marked change and produce this new report. I also wanted to offer state-by-state data for liver cancer mortality, so that the U.S. Public Health Community might have information that will help them in their important work throughout America. While we have seen decreases in death rates from many major causes — such as heart disease, cancer (all cancer combined), and stroke recently – liver cancer deaths stand out far away from the decreasing trends of these causes of death. To elaborate, the age-adjusted death rates for all cancer combined, have declined since 1990. Also, for the top six cancer death causes in 2016 (lung cancer, colorectal cancer, pancreatic cancer, breast cancer, prostate cancer, and liver cancer), the age-adjusted death rates decreased for four of them (lung, colorectal, breast, and prostate) and increased for two (liver cancer and pancreatic cancer) — with the liver cancer death rate increasing much faster than the pancreatic cancer death rate, since 2000.
Q: Was there a finding in your new report that you hadn’t expected and that really surprised you?
JX: There actually are quite a few interesting results in this new analysis that surprised me. While there are some reports out there that show the increase of liver cancer mortality, we also know that the liver cancer death rate demonstrates a trend of continued rate increase during the period from 2000 through 2016 – which is the time span this report analyzed. The surprise is that the liver cancer death rate for men is between 2 and 2.5 times the rate for women aged 25 and over, during the period of 2000–2016. Within the four race/ethnic groups analyzed, the only decrease trend in liver cancer mortality observed, is for the non-Hispanic Asian or Pacific Islander (API) group. The rate increased for non-Hispanic white, non-Hispanic black, and Hispanic persons. Also the liver cancer death rates varied quite a bit by state, which is another surprising finding.
Q: What made you decide to focus on the age group of adults 25 years old and older?
JX: I had a number of reasons to focus on the liver cancer death rate for adults aged 25 and over. More than 99% of all deaths with liver cancer reported on the death certificate are for adults 25 years of age and over. It made sense to focus this analysis on the majority age group that dies from this cancer cause. We also know that age is a leading risk factor for the development of many types of cancer. Aging increases cancer risk. This is exactly what we see here in this new report. And the liver cancer death rate for older age groups is significantly higher than the rate for younger age groups throughout the period examined in this analysis.
Q: What differences or similarities did you see between or among various demographic groups in this analysis?
JX: The differences among demographic groups is also what I found most surprising in this report. The liver cancer death rate for men aged 25 and over is between 2 and 2.5 times the rate for women. The liver cancer death rate varies by race/ethnic groups. The Non-Hispanic Asian or Pacific Islander (API) group have the highest liver cancer death rate among the four race/ethnic groups analyzed during 2000–2014. The rate for Hispanic adults surpassed the rate for non-Hispanic API and became the highest in 2016. The liver cancer death rate for non-Hispanic white adults was the lowest among the race/ethnic groups throughout the period (2000–2016).
Q: Why do you think there is such a vast difference among the states in death rates from liver cancer?
JX: The mortality data we analyzed does not provide any evidence itself to show the reason or reasons that could contribute to the variation of liver cancer death rates by state. In general, the majority of the liver cancer in the United States is often attributed to some potential risk factors such as metabolic disorders (including obesity, diabetes, and nonalcoholic fatty liver disease), chronic Hepatitis C (HCV) infection, excessive consumption of alcohol, smoking, and chronic Hepatitis B (HBV) infection. If the number of people affected by those potential risk factors is different from one state to another, the liver cancer incidence rate and death rate would vary.
Q: What do you think is the reason for the growing increase in deaths from liver cancer in the United States?
JX: The mortality data we analyzed does not provide any evidence itself to show the reason or reasons that could contribute to the rising of the liver cancer death rate in this country. Some risk factors might contribute to the increase in liver cancer incidence rate and death rate. For example, some attribute the baby boomer generation’s higher hepatitis C virus infection rate than other adult age groups. Some have identified an increase in the obesity rate as another reason. Unfortunately, we can’t answer this question with our data, though it is an important question.
Q: What would you say is the take-home message of this report?
JX: I think the real take-home message of this Data Brief is what it can offer to the Public Health Community to learn about liver cancer mortality variance among different groups. The report shows that liver cancer mortality varies by sex, age, race/ethnic groups, and by state. Although the overall liver cancer death rate increased from 2000 to 2016, the rate for non-Hispanic Asian or Pacific Islander (API) decreased. The rate for adults aged 45–54 has decreased since 2012.