Efficacy of screening for cervical cancer: a review.

Cytologic screening for cervical cancer currently enjoys wide acceptance, but there remains controversy in the literature concerning its efficacy in prolonging life. On the basis of a literature review, several conclusions are reached: 1) Cervical screening can identify women who are at greater-than-average risk of developing invasive cervical cancer by detecting asymptomatic lesions that would frequently progress to invasion if left untreated; 2) Therapy based on confirmed positive smears can reduce the incidence and mortality rates of invasive cervical cancer, as shown by declining rates in many centers that had constant or increasing rates before screening began, lower rates for geographic areas and occupational groups having less screening, and lower rates among screened women than unscreened women; and 3) Attempts to estimate the amount of life prolongation attributable to cervical screening have not yet yielded reliable figures, because of difficulties with the models or data used. However, in view of the available evidence, it is suggested that incomplete data should not prevent a vigorous continuation of screening where it is already extensive, and an escalation where it is not.