Question

Explain how chronic infection induced by hepatitis B virus (HBV) or hepatitis C virus (HBC) contributes to the development of cancer.

Answer 1

ANSWER - Hepatitis B is an infection caused by the hepatitis B virus. Hepatitis C is an infection caused by the hepatitis C virus. Both diseases are contagious and can lead to serious, long-term illness.

* Chronic infection can occur if the virus stays in the body. Chronic infection with both viruses can cause serious, long-term liver disease, such as cirrhosis. In this condition, cells of the liver die and are replaced by scar tissue. Over time, the liver stops working. In some cases, chronic hepatitis infection can lead to liver cancer

* The hepatitis B virus is spread by direct contact with the body fluids (blood, semen, or vaginal fluids) of an infected person. This can happen during unprotected sex or while sharing needles used to inject ("shoot") drugs. A baby can be infected during birth if the mother has the hepatitis B virus. The hepatitis B virus also can be spread if you live with an infected person and share household items that may come in contact with body fluids, such as toothbrushes or razors.
* The hepatitis C virus is spread by direct contact with infected blood. This can happen while sharing needles or sharing household items that come into contact with blood. A baby can be infected during birth if the mother has the hepatitis C virus. It also can be spread during unprotected sex, but it is harder to spread the virus this way.
* Most cases of hepatocellular carcinoma (HCC) are associated with cirrhosis related to chronic hepatitis B virus (HB V) or hepatitis C virus (HC V) infection. 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 HB V or HC V infection.
* Hepatocellular carcinoma (HCC) is the most common form of liver cancer; most cases of HCC (approximately 80%) are associated with chronic hepatitis B virus (HB V) or hepatitis C virus (HC V) infections.

Variations in the age-, sex-, and race-specific rates of HCC rates in different geographic regions are likely to be related to differences in the prevalence of hepatitis viruses in the populations, as well as the timing of the spread of the viral infection and the age of individuals at the time of the infection.
* HB V and HC V promote cirrhosis, which is found in 80%–90% of patients with HCC. The 5-year cumulative risk of developing HCC for patients with cirrhosis ranges between 5% and 30%, depending on etiology (it is highest in individuals with HC V infection), region or ethnicity (it is highest in Asians), and stage of cirrhosis (it highest in individuals with decompensated disease).

The HC V epidemic in the US originated from contaminated needles and/or injection drug use. The virus spread into national blood supplies and circulated until the late 1980s; the rate of new infections was greatly reduced thereafter.

The age distribution of HCC in different regions is partly determined by type of virus and timing of infection. In areas that have high incidence of HCC in Asia, HB V infection is largely acquired by mother–child transmission, whereas transmission among siblings of young ages is more common in Africa. Therefore, individuals in these regions develop HCC at earlier ages than in low-incidence areas, where the main risk factors for HC V infection are encountered later in life. Differences in age-related prevalence of HCC might affect applicability and outcomes of therapies such as liver transplantation. The high male:female ratio of HCC might result, in part, from the higher prevalence of HB V and HC V infection among men than women.

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