Page 69 - Screening for Cervical Cancer: Systematic Evidence Review

Chapter IV. Discussion

IV. Discussion

Context

To place choices about cervical screening in context, we need to highlight 4 factors not

explicitly investigated in this systematic evidence review (SER).

First, the successes of cervical cancer screening to date, using conventional cytology,

have been achieved using a diagnostic test that in other settings would be considered weak.

Synthesis of the highest quality literature evaluating traditional Pap testing produces estimates

that its sensitivity is 51 percent and specificity is 98 percent. 32,50

Second, these test characteristics have proven adequate because cervical dysplasia is a

slowly progressing and often self-resolving condition. The estimated progression time from

severe dysplasia or carcinoma in situ to invasive cancer is 10 to 15 years. 21,32 Thus, repeated

screening builds in redundant opportunities to detect abnormalities.

Third, cervical dysplasia itself does not cause morbidity or mortality. Low-grade

squamous intraepithelial lesions are the most common changes detected by cytology in regularly

screened populations, but they are also the most likely to resolve spontaneously. These low-

grade changes are most common among young women, as are intermittent, recurrent, and

resolving infection with human papilloma virus (HPV).

Fourth, an ideal screening system will optimize detection of high-grade lesions and

minimize evaluation of low-grade and false-positive test results. However, this ideal can be

achieved only with improved use of screening among the currently unscreened and with reliable

systems for assuring follow-up of abnormal screening findings.

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