Page 64 - Screening for Cervical Cancer: Systematic Evidence Review
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Chapter III. Results
management of patients with low grade cytologic abnormalities who will at the time of
colposcopy have a much lower prevalence of high grade lesions.
The indications for the colposcopy, including indications established for the purposes of
research, vary across studies; this in turn also influences the spectrum of abnormalities identified.
The study cohort in Iceland had a prevalence of 54.5% of high-grade lesions compared to 15.4%
among German women referred for colposcopy. Similarly, among studies that enrolled patients
based on cytology findings as an entry criterion (rather than referral for colposcopy), the criteria
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vary from ASCUS only to CIN 1 or CIN 2. This means that aggregating test performance
characteristics across studies is problematic. The test characteristics of high-risk HPV testing for
detecting HSIL as a triage tool are summarized in Table 11.
Three strong studies selected the degree of Pap test abnormality a priori and then
obtained histologic verification of HPV test performance. The group with the lowest risk of
high-grade lesion at the time of evaluation was that assembled by Manos and colleagues within
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the Kaiser Permanente Medical Care Program in Northern California. They enumerated all
women at 4 medical centers who had a Pap test during a 9-month period and invited all women
with ASCUS to participate if they were not pregnant and did not have a history of treatment for
cervical neoplasia in the prior six months. Sixty-one percent of patients with ASCUS enrolled in
the study; participants were demographically similar to non-participants. In this setting the
sensitivity of Hybrid Capture II testing for high-risk HPV to detect HSIL was 89.2%; specificity
was 64.1%; positive predictive value, 15.1%; negative predictive value 98.8%. For detection of
LSIL and more severe lesions, the sensitivity was 76.3%; specificity, 69.5%; positive predictive
value, 37.8%; and negative predictive value, 92.4%.
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