Human papillomavirus (HPV) is the name of a group of viruses that includes more than 150 types. Around 40 of these viruses infect the genital area of men and women. HPV can cause premalignant changes and malignant cancers of cervix, vagina, vulva and anus.
Almost all cervical cancers are caused by persistent infection with one of the cancer-causing (or high-risk) HPV types. HPV infection is usually found in persons who have ever been sexually active. Most people with HPV infection do not have any symptoms and will clear the infection on their own.
Some females with persistent high-risk HPV infection in the cervix will develop pre-cancerous cell changes. While the majority of these changes will regress to normal within 1 to 2 years, some may progress to cancer over years.
The following figure illustrates the natural course of the development of normal cervical cells to cervical cancer: