Cervical cancer screening: from the Papanicolaou smear to the vaccine era.

In the next 20 years, cervical cancer screening will have evolved through four phases. The first was traditional screening, which has been associated with a two-thirds reduction in cancer incidence and death rates in the last 50 years and currently is ending. We are entering a second phase, human papillomavirus (HPV) testing, for managing cytologic abnormalities and possibly for primary screening. A third phase, new in development, proposes the use of host biomarkers (or combinations thereof) as either surrogates of HPV infection or, potentially, indicators to assess cancer risk and concentrate available resources on a subset of women. The fourth and, likely, final phase will be screening in an era of vaccines. If HPV vaccines are successful, the pool of at-risk individuals and the prevalence of papillomaviruses that place them at risk will gradually shrink. In this climate, screening strategies that target HPVs alone (as opposed to cytologic testing) may become more economical. If so, previous strategies may become obsolete as the balance of cervical cancer prevention shifts from traditional screening to primary prevention coupled with HPV testing.