The natural history of human papillomavirus infection.

Human papillomavirus (HPV) is a small double-stranded DNA virus that commonly infects humans. The oncogenic characteristics of HPV derive from the oncoproteins E6 and E7 that act inhibiting p53 and pRB tumor suppressors. About 5% of all cancers worldwide are attributable mainly to those known as high-risk, including HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59. Infection with HPV is common after sexual initiation, but the majority of HPV infections do not cause symptoms or disease and are cleared within 12-24 months post-infection. Only a small fraction of those infections that persist or progress to a preneoplastic lesion result in cancer. Persistence of HPV infection is needed to start the oncogenic process. Clearance of infection is common in young adults. Viral load and viral type are the main cofactors for progression from infection to cervical intraepithelial lesions and cancer. Smoking, hormonal exposure, and HIV are additional exposures that increase the risk of progression to cancer. The adverse health effects of HPV infections can be largely controlled through vaccination and screening.