Epidemiology and natural history of HPV.

Human papillomavirus (HPV) is a highly prevalent, sexually transmitted infection responsible for significant morbidity and mortality. High-risk HPV types are now known to be necessary in the etiology of cervical cancer and to lead to both high-grade and low-grade cervical lesions. They are also implicated in a substantial portion of anal, penile, and head and neck precancers and cancers. HPV 16 and 18 are the most common HPV types found in cervical cancer and are responsible for approximately 70% of these cancers. In contrast, low-risk HPV types, the most common of which are HPV 6 and 11, cause genital warts, low-grade cervical lesions, and recurrent respiratory papillomatosis, but they do not cause cervical or other HPV-related cancers. Infection is most common in young, sexually active populations, and an estimated three fourths of adults will be infected with HPV during their lifetime. Cervical screening programs exist in the United States and other developed countries to identify and treat precancerous cervical lesions, but they do not reach all women and are costly. Until recently, no highly effective primary prevention strategy to reduce the risk of HPV acquisition existed. However, a quadrivalent HPV vaccine, which protects against the most common high-risk and low-risk HPV infections (HPV 16, 18, 6, and 11), is now available. In addition, a bivalent HPV vaccine that protects against high-risk HPV types 16 and 18 is in the late stages of clinical development. If implemented widely, vaccination against HPV promises to dramatically reduce HPV-associated morbidity and mortality.