Human papillomavirus (HPV) infection is very common in the population and is mainly transmitted through sexual contact. In the vast majority of cases, infection is temporary and asymptomatic. A persistent infection, however, can cause a variety of lesions on the skin and mucous membranes, depending on the type of HPV involved. Some types of HPV are classified as “high risk” because they are associated with the development of cancer. Cervical cancer (cervical carcinoma or carcinoma of the uterine cervix) is the cancer most commonly associated with HPV, and the first cancer recognized by the World Health Organization (WHO) to be 100% attributable to an infection.
Human papillomavirus is a group of small DNA viruses. Over 100 types of HPV have been identified that infect humans, and about 40 of these are known to be associated with both benign and malign anogenital conditions. HPV types are classified as “high risk” or “low risk”, based on their potential to lead to neoplastic transformation. The International Agency for Research on Cancer (IARC) has confirmed that 12 HPV types can cause cancer. Some types have a greater tendency to progress to cervical carcinoma compared to others. Indeed, HPV types 16 and 18 are estimated to be responsible for over 70% of cervical cancer cases, and together with HPV types 45, 31, 33, 52, 58 and 35, for almost 90% of all cases. Low-risk HPV types are associated with benign lesions, such as genital warts.