State-of-the-Art Lecture 1
Speaker: Hashem El-Serag, MD, MPH (USA) Chair: Morris Sherman, MD, PhD (Canada)
Global Trends in Epidemiology in Liver Cancer: HCC and ICC
Hashem El-Serag, MD, MPH (USA)
Primary liver cancer, which consists predominantly of hepatocellular carcinoma (HCC), is the fifth most common cancer worldwide and the third most common cause of cancer mortality. HCC has several interesting epidemiologic features including dynamic temporal trends; marked variations among geographic regions, racial and ethnic groups, and between men and women; and the presence of several well-documented environmental potentially preventable risk factors.
The highest age adjusted incidence rates (>20 per 100,000) were reported from countries in Southeast Asia and sub-Saharan Africa that are endemic for HBV infection. Countries in Southern Europe have medium-high incidence rates, while low-incidence areas (<5 per 100,000) include South and Central America, and the rest of Europe. Cirrhosis due to chronic hepatitis B or hepatitis C is the leading risk factor for HCC. Changes in the time trends of HCC and most variations in its age-, sex-, and race-specific rates among different regions are likely to be related to differences in hepatitis viruses that are most prevalent in a population, the timing of their spread, and the ages of the individuals the viruses infect. Environmental, host genetic, and viral factors can affect the risk of HCC in individuals with HBV or HCV infection. Other risk factors include heavy alcohol drinking, aflatoxin exposure (in HBV infected individuals), obesity and diabetes. There is epidemiologic evidence to support an association between nonalcoholic fatty liver disease (NAFLD) or NASH and an increased risk of HCC; risk seems to be limited to individuals with cirrhosis.
HBV continues to be the major HCC risk factor worldwide, although its importance will most likely decrease during the coming decades due to the widespread use of the HBV vaccine in the newborns. HCV has been the dominant viral cause in HCC in North America, some Western countries and Japan. Obesity and diabetes are increasing at a fast pace throughout the world, and if they are proven to be HCC risk factors, they would account for more HCC cases in the future.
The main primary preventive methods include HBV vaccination, HBV and HCV treatment, reduction in alcohol intake and aflatoxin exposure, while secondary prevention focuses on surveillance. HCC continues to carry a dismal prognosis despite surveillance and the established curative treatment. There is growing evidence of a rift between the results of preventive (and therapeutic) methods in clinical trials and specialised centers (i.e., efficacy results) and those of every day clinical practice (i.e., effectiveness) with underutilisation, overutilisation and disparities present across the spectrum of care.