UICC World Cancer Congress 2006

Worldwide, hepatic cancer (most commonly, hepatocellular cancer and generically known as “liver cancer”) ranks as the fifth most common cancer, estimated at more than 400,000 new cases per year with nearly an equal number of deaths due to liver cancer annually. Thus, survival rates for liver cancer are typically less than five years. Liver cancer represents one of the few cancer types that is increasing in incidence and mortality compared with the overall trend in the decline of cancer cases. In contrast to the typical cancers that are chronic in origin, liver cancer represents an infectious form of cancer that reflects opportunities for prevention through vaccination, serological testing, and lifestyle and environmental changes.

In 2005, the USDHHS Report on Carcinogens listed the hepatitis B virus (HBV) and the hepatitis C virus (HCV) as substances known to be human carcinogens, making them the first viruses declared to be etiologically related to liver cancer. Liver cancer that is attributable to hepatitis B viral (HBV) infections is most common in southeastern Asia, China, sub-Saharan Africa, and Alaska and is associated with its higher endemicity of HBV in those regions. China alone accounts for more than half of the worldwide incidence of liver cancer. Liver cancer is much less common in North and South America and Europe. Liver cancer can also be attributable to other risk factors such as excessive consumption of alcohol and aflatoxins, cigarette smoking, obesity, use of oral contraceptives, liver flukes, iron overload, and exposure to the hepatitis C virus (HBV) among populations using intra-dermal injections. Men are affected much more than women. In the United States, the highest incidence of liver cancer occurs among Asian Americans and African Americans and the least among non-Hispanic Whites.

Data from Taiwan have provided empirical evidence of the efficacy of HBV vaccination programs for youth. Beginning in 1991, U.S. health care providers initiated universal infant HBV vaccination while infants were typically still in hospitals. Along with school entry requirements for evidence of HBV vaccinations as well as “catch-up” programs, the proportion of youth who will be vaccinated will increase. However, not all segments are being reached and aggressive follow-up programs are still warranted. In the long term, vaccination should reduce the burden of liver cancer.

To address adults, the National Cancer Institute recently funded a program project, “Liver Cancer Control Interventions for Asian Americans” that has as its outcome, increasing serological testing for Vietnamese, Hmong, and Korean, ages 18-64. Through this research, ethnically specific interventions including use of in-language media, lay health workers, and church-based interventions will be tested and lessons learned.

Both basic and applied research as well as carefully designed evaluations of interventions on a global basis will be needed to address the complex and variable web of liver cancer etiology, prevention, and control in different regions. For example, no vaccine currently exists to address HCV infections; no vaccine exists to address liver fluke infections, aflatoxins, or alcohol or cigarette smoking or obesity. Addressing lifestyle and environmental changes remain necessary to prevent and control liver cancer.