Page 40 - Screening for Cervical Cancer: Systematic Evidence Review

Chapter III. Results

In toto, the included studies tell different versions of the same story about the influence of

age on risk for high-grade cervical lesions and cancer:

• Incidence of cervical intraepithelial neoplasia (CIN), including CIN 3 and carcinoma

in situ (CIS), peaks in the mid-reproductive years and begins to decline in

approximately the fourth decade of life. 26,34-36

• The prevalence of CIN follows a similar pattern: diagnosis of CIN 3 and CIS is

shifted toward older age at diagnosis relative to CIN 1 and 2 but still decreases with

age. 37-40

• This general pattern is also apparent among previously unscreened women. 40,41

• Based on the incidence of cancers that arise between screening intervals, cervical

cancer in older women is not more aggressive or rapidly progressive than that in

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younger women.

• The rates of high-grade squamous intraepithelial lesions (HSIL) diagnosed by

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cytology are low among older women who have been screened: 0.2-1.9, 0.7-1.7,
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and 0.8-1.4, per 1,000 among women ages 50 years and older.
These observations are consistent with ecologic data and natural history studies of

cervical dysplasia and cancer and studies of HPV progression. Three of the included studies rely

only on cytology results. 26,36,37 The remainder have varying degrees of histologic

documentation; these range from complete or near complete histologic documentation of all

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cases, 38,40-44 to good verification of cases (72% verified to 82% verified ) to inadequately
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described use of histologic “gold standard.” None attempted to identify false negatives through

evaluation of women with negative screening tests. As such, this literature reflects the quality of

the cytology services deployed to screen the retrospective and prospective cohorts that make up

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