National Cancer Institute
Some cancer-associated viruses appear, in rare cases, to cause cancer. Other viruses, however, substantially increase the risk for cancer and the burden of this disease in the population. For example, HIV-1 infection is responsible for substantial increases in some cancers in young adults in the United States. Although it is not yet clear how to prevent most cancers that occur among HIV-infected people, understanding the transmission routes of the virus and finding preventive measures could lower the incidence of infection, and the subsequent risk of non-Hodgkin’s lymphoma and Kaposi’s sarcoma. Previously, only a small percentage of cancers were thought to be caused by infectious agents, but current analyses put that number closer to 18 percent.
Similarly, reducing the transmission of human T-lymphotropic viruses will lower the incidence of adult T-cell leukemia/lymphoma. Furthermore, knowing which cancers are associated with different viruses helps to promote targeted cancer screening, early detection, treatment, and prevention.
Scientists in the NCI’s Infections and Immunoepidemiology Branch are using principles of both infectious and chronic disease epidemiology to investigate the biology and transmission of cancer-causing organisms and to clarify the relationship between infectious organisms and cancer and other diseases. In addition to studying viruses that are associated with cancer, these scientists are also investigating other microorganisms, such as Chlamydia pneumoniae, which have been linked to lung cancer, and sexually-transmitted viruses that may cause prostate cancer.
NCI’s Center for Cancer Research supports researchers who are making important advances in understanding the relationship between infection and cancer. These scientists are investigating tumor-causing viruses and bacteria at the molecular level. Areas of investigation include genes and gene products that regulate cell growth and pathways that contribute to the development of cancer.
The knowledge gained in studying the links between viruses and certain types of cancer has been instrumental in helping scientists develop strategies to fight cancer, such as vaccines directed against human papillomaviruses to prevent cervical cancer and hepatitis B virus, which has been associated with some forms of liver cancer. The study of viruses has also been an important tool in revealing the mechanisms that are involved in carcinogenesis.
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