Cervical Cancer Screening and Human Papillomavirus (HPV ... - KCE

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12 Cervical cancer screening and HPV KCE reports vol.38 Table 4. Meta-analysis of test sensitivity and specificity of cervical cytology at 2 test thresholds (LSIL+ and HSIL+) for colposcopically or histologically confirmed presence of CIN2+ or CIN1+pooled from studies with complete and incomplete gold standard verification (adapted from 18, 19 . A. Outcome presence of CIN2+ All studies Test threshold Sensitivity (95% CI) # studies Range Specificity (95% CI) # studies LSIL+ 0.83 (0.80-0.86) 46 0.22-1.00 0.61 (0.55-0.67) 46 HSIL+ 0.58 ( 0.49-0.66) 45 0.89 (0.87-0.90) 45 Only studies without verification bias Test threshold Sensitivity (95% CI) # studies Specificity (95% CI) # studies LSIL+ 0.77 (0.58-0.97) 6 0.92 (0.89-0.95) 6 HSIL+ 0.87 ( 0.78-0.96) 1 1.00 (0.99-1.00) 1 B. Outcome presence of CIN1+ All studies Test threshold Sensitivity (95% CI) # studies Range Specificity (95% CI) # studies LSIL+ 0.67 (0.63-0.71) 72 0.73 ( 0.71-0.76) 72 HSIL+ - - 0 - - 0 Only studies without verification bias Test threshold Sensitivity (95% CI) # studies Specificity (95% CI) # studies LSIL+ 0.52 (0.38-0.66) 9 0.96 (0.94-0.98) 9 HSIL+ - - 0 - - 0 The test sensitivity of cytology for CIN (without precision of test and outcome thresholds), estimated by modelling from the historical British Columbia cohort was 80% 33, 6 . It concerned here sensitivity evaluated in an organised screening setting with good quality control. 2.3.3 Conclusions To conclude, it can be stated that the test sensitivity and specificity of the conventional Pap smear are not known precisely. The sensitivity for CIN2+ at low cytological thresholds is, on average, relatively high (often in the range 70-80%), but it also can be low in certain situations. The estimation of the accuracy varies by population characteristics (age, screening history, screening or follow-up situation) and study design properties (selection bias, definition of cut-offs, method of gold standard assessment (colposcopy oriented biopsies completed or not with random biopsies; punch versus excision biopsies), verification bias, masked or unmasked gold standard assessment). 30
KCE reports vol.38 Cervical cancer screening and HPV 13 Nevertheless, convincing evidence is available with respect to the effectiveness of cytological screening, if offered in a well organised setting with quality control at all levels. 2.4 LIQUID-BASED CYTOLOGY 2.4.1 Description Liquid-Based cytology (LBC) was introduced in the mid-1990s as a way to improve the performance of the conventional test. The cells are transferred into a vial with a liquid preservative solution that is transported to the laboratory where the slide is prepared. The cells are not spread directly onto a slide to obtain a conventional Pap (CP) smear but transferred into a vial with a fixative liquid. This vial is then sent to a specially equipped laboratory. Several systematic reviews regarding the performance of LBC to detect cervical cancer precursors were performed over the last 8 years 34, 35, 18, 36-47 }. Conclusions formulated by the reviewing authors were disparate and depended largely on selection criteria to include individual studies and the considered performance parameters. Studies comparing detection rates for low grade cytological abnormalities often yielded more favourable results for LBC 34, 36, 39, 48 , whereas in studies focusing on accuracy for biopsy-confirmed high-grade CIN (cervical intraepithelial neoplasia), no significant differences between the CP (conventional Pap smear) and LBC were found 40, 43, 47 . 2.4.1.1 Liquid-based cytology techniques 2.4.1.2 Study design A number of different LBC techniques are in use worldwide. These include ThinPrep®, Surepath® (formerly, CytoRich and AutoCyte PREP), Cytoscreen®, Cyteasy®, Labonord Easy Prep, Cytoslide, SpinThin and PapSpin. So far, ThinPrep® and Surepath® are approved for use in the USA by the Food and Drug Administration (FDA) allowing the claim of increased detection of squamous intraepithelial lesions and a reduction of the number of unsatisfactory smears compared to the CP 49, 50 . In the ThinPrep the liquid preservative solution is filtered through a membrane filter with a pore size specifically designed to trap epithelial cells. The epithelial cells collected on the membrane filter are then transferred on a glass slide and stained. In the Surepath system, concentration of cells is based on sedimentation through a density gradient. Numerous studies have evaluated the comparative performance of the two most commonly used LBC methods, ThinPrep and Surepath, and conventional cytology with respect to test positivity, their sensitivity and specificity for identification of CIN, the specimen adequacy and the time required for evaluation of the specimens. Although there is a reasonable agreement that LBC improves specimen adequacy and reduces screening time compared to conventional cytology, there is considerable controversy surrounding the relative sensitivity and specificity of the two approaches, largely due to a lack of well designed studies 30 . Most of the comparative studies have utilized one of two types of study design: The concomitant testing design (mainly split-sample ) The two-cohort design ( direct-to-vial ) In the concomitant testing design, 2 samples are prepared from the same subject. Most often one single sample is taken from the uterine cervix and a CP (conventional smear) is prepared first, followed by transfer of the residual cellular material remnant on the sampling device into a vial with fixative liquid ("split-sample"). Occasionally, two separate samples are collected: one for the CP and another one for LBC. In the twocohort design, CP samples and LBC samples are taken from separate populations.
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KCE reports 34 Trastuzumab in Early
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