Reference Manual - IARC Screening Group

Introductionitching or burning in the genital area. After a woman becomes infectedwith HPV, the infection may remain locally stable, may regressspontaneously, or if the cervix is affected, may develop into low-gradesquamous intraepithelial lesions (LGSILs), which are also called mildcervical intraepithelial neoplasia (CIN I) or early dysplasia. Most lowgrade(CIN I) lesions disappear without treatment or do not progress,particularly those that occur in younger women (Figure 1-2). It isestimated that for every 1 million women infected, 10% (about 100,000)will develop precancerous changes in their cervical tissue. Theseprecancerous changes are observed most frequently in women betweenages 30 and 40.Figure 1-2. Natural History of Cervical Cancer—Current UnderstandingSource: PATH 1997.About 8% of the women who develop these changes will develop precancerlimited to the outer layers of the cervical cells (carcinoma in situ[CIS]), and about 1.6% will develop invasive cancer unless theprecancerous lesion or CIS is detected and treated. Progression tocervical cancer from high-grade squamous intraepithelial lesions(HGSILs) generally takes place over a period of 10 to 20 years (Figure1-3). Although rare, some precancer lesions become cancerous over ashorter time interval—within a year or two (Hildesheim et al. 1999).Although HPV-related lesions (e.g., warts) can be treated, currently thereis no cure for HPV infection. Once infected, a person is most likelyinfected for life. In most cases, an active infection is controlled by theimmune system and becomes dormant over time. It is not possible,however, to predict whether or when the virus will become active again.1-2 Cervical Cancer Prevention Guidelines for Low-Resource Settings