How do high-risk HPVs cause cancer?
HPVs infect epithelial cells. These cells, which are organized in layers, cover the inside and outside surfaces of the body, including the skin, the throat, the genital tract, and the anus. Because HPVs are not thought to enter the blood stream, having an HPV infection in one part of the body should not cause an infection in another part of the body.
Once an HPV enters an epithelial cell, the virus begins to make proteins. Two of the proteins made by high-risk HPVs interfere with normal functions in the cell, enabling the cell to grow in an uncontrolled manner and to avoid cell death.
Many times these infected cells are recognized by the immune system and eliminated. Sometimes, however, these infected cells are not destroyed, and a persistent infection results. As the persistently infected cells continue to grow, they may develop mutations that promote even more cell growth, leading to the formation of a high-grade lesion and, ultimately, a tumor.
Researchers believe that it can take between 10 and 20 years from the time of an initial HPV infection until a tumor forms. However, even high-grade lesions do not always lead to cancer. The percentage of high-grade cervical lesions that progress to invasive cervical cancer has been estimated to be 50 percent or less (11).
How do high-risk HPVs cause cancer?
HPVs infect epithelial cells. These cells, which are organized in layers, cover the inside and outside surfaces of the body, including the skin, the throat, the genital tract, and the anus. Because HPVs are not thought to enter the blood stream, having an HPV infection in one part of the body should not cause an infection in another part of the body.
Once an HPV enters an epithelial cell, the virus begins to make proteins. Two of the proteins made by high-risk HPVs interfere with normal functions in the cell, enabling the cell to grow in an uncontrolled manner and to avoid cell death.
Many times these infected cells are recognized by the immune system and eliminated. Sometimes, however, these infected cells are not destroyed, and a persistent infection results. As the persistently infected cells continue to grow, they may develop mutations that promote even more cell growth, leading to the formation of a high-grade lesion and, ultimately, a tumor.
Researchers believe that it can take between 10 and 20 years from the time of an initial HPV infection until a tumor forms. However, even high-grade lesions do not always lead to cancer. The percentage of high-grade cervical lesions that progress to invasive cervical cancer has been estimated to be 50 percent or less (11).
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