Sunday, March 27, 2011

Cancers Caused by Infectious Agents

We do not generally regard cancer as being contagious.  Although this is generally t rue, there are a growing number of cancers that have been shown to be caused by contagious agents, especially by specific viruses.  In the table below, the kinds of cancers caused by such agents are shown along with the microorganism implicated and their prevalence by location.


Causative Agent

Stomach (Gastric) Cancer

H. Pylori - Bacterium

Cervical Cancer

Human Papilloma Virus (HPV)

T-Cell Leukemia

HTLV-1 – related to the AIDS virus

Burkitt's Lymphoma

Epstein Barr Virus (EBV)

Kaposi's Sarcoma

HTLV-3 – AIDS Virus

Primary  Liver Cancer

Hepatitis B Virus (HBV)


In regards to the data listed in the table above, there is additional information associated with them:

  •          H.Pylori is a highly specialized and fairly ubiquitous bacterium that can survive in the harsh acidic environment of the stomach; it is found in the mucus layer on the inside of the stomach within those individuals who are infected.  For this reason, it is particularly difficult to treat with antibiotics.  It is found in about 2/3 of the world's population.  It has also been implicated in the onset of chronic gastritis and peptic ulcers.
  •          HPV has recently been implicated as the causative agent for cervical cancer.  Cervical Cancer is prevalent in sexually active women.  A vaccine against this virus has recently been developed.  It has been shown to be highly effective in preventing the onset of this cancer in young women. 
  •          EBV, the virus that causes Burkitt's lymphoma found predominantly in Africa, is the same virus that causes mononucleosis in individuals in the West.  The reason for this distinct difference in disease outcomes is poorly understood, but a genetic basis for this difference is likely.
  •          The AIDS virus is not directly responsible for the onset of Kaposi's sarcoma.  The disease is manifested in AIDS patients on account of their highly suppressed immune system due to infection with the AIDS virus that make AIDS patients especially susceptible to this cancer.
  •          Once an individual is infected with HBV as a result of close human contact with an infected individual, the virus can infect the liver without any noticeable symptoms.  This can be the case for many years before the onset of Liver cancer.   HBV is believed to account for 80% of primary liver cancer (cancer that originates in the liver).  It is a deadly cancer.  Fortunately, there is a vaccine against HBV infection, but there is currently no vaccine to prevent infection by the Hepatitis C Virus (HCV) that is also known to cause primary liver cancer. 

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