Abstract
While there are several types of hepatitis viruses, e.g., Hepatitis A; Hepatitis B; Hepatitis C; Hepatitis D; Hepatitis E; two of these viruses: Hepatitis B (HBV) and Hepatitis C (HCV) have the distinction of being definitively “carcinogenic” and are the first such viruses so classified by the U.S. Department of Health and Human Services and the World Health Organization (WHO). Acting separately or together, HBV and HCV have been etiologically responsible for chronic infections, cirrhosis, chronic liver disease, and hepatocellular carcinoma (primary liver cancer).
Liver cancer is a global public health problem that is also becoming increasingly prominent as a significant cancer health disparity among U.S. racial/ethnic minority populations. On a global basis, liver cancer ranks sixth in cancer incidence but third in cancer mortality. The ratio of liver cancer incidence to mortality is 95%–98%. While not as prevalent in the U.S., liver cancer mortality increased by 17 per cent between 1995 and 2004, leading all other cancer sites while the cancer mortality rates were decreasing for the great majority of other sites. Furthermore, liver cancer disproportionally affects peoples of color and account for disparities in both incidence and mortality where the rates for liver cancer incidence for each racial/ethnic minority population of color substantially exceed the comparable rates for Whites.
Challenges and opportunities in reducing liver cancer health disparities are presented from an epidemiological profile of the global and U.S. prevalence of HBV and HCV; differential patterns of these two viral types, and opportunities for prevention. In epidemiological terms, HBV has infected an estimated two billion people world-wide, resulting in more than 350 chronic liver infections. HBV is endemic in eastern Asia but also affects large portions of Africa, the Amazon, and southern and eastern Europe. HBV is more easily transmissible than HIV and can be transmitted through from mother to infant during the birthing process; through sexual intercourse; and through other means. The HBV vaccine used starting since 1982 has been demonstrated to significantly reduce rates of infection compared to unimmunized children and is considered the most effective means of preventing this disease.
By contrast, no vaccine exists for HCV. HCV is the most common chronic blood-borne viral infection and like HBV, is more easily transmissible than HIV. HCV is more typically associated with infections due to injection drug use as well as through contaminated blood transfusions or hemophilia, though system improvements have reduced these latter modes of transmission.
Frequently HBV and HCV does not present with overt symptoms and hence blood tests are needed for definitive diagnoses. Unfortunately though serological testing for HBV and HCV are not routinely ordered by health care professionals and much more continuing education of health professionals and lay people alike are needed to create awareness. Though chemotherapeutic options continue to increase in effectiveness, liver transplantation remains as one of the few options for extended survival. However, access to liver transplantation as well as routine diagnostic and treatment modalities for HBV and HCV remain as obstacles.
In spite of these challenges, the World Health Organization considers HBV as the second most important cancer risk factor after tobacco use and infections in general are considered the second most preventable cause of cancer. Strategies for reducing disparities associated with HBV based on the strategies associated with eradicating smallpox are suggested while considerable more research on preventing HCV is needed.
Second AACR International Conference on the Science of Cancer Health Disparities— Feb 3–6, 2009; Carefree, AZ