Accuracy of liquid-based cytology: comparison of the results obtained within a randomized controlled trial (the New Technologies for Cervical Cancer Screening Study) and an external group of experts.

BACKGROUND: In the New Technologies for Cervical Cancer Screening (NTCC) randomized controlled trial, no significant increase in the sensitivity of liquid-based cytology (LBC) was observed compared with conventional cytology. Both were interpreted by cytologists who had limited previous LBC experience. The objective of the current study was to assess whether different results could be expected with experienced LBC interpreters. METHODS: A stratified, random sample of 818 LBC slides from the NTCC study was obtained. These slides were reviewed blindly and independently by 3 international experts who did not participate in the NTCC. The sensitivity and specificity of external experts were estimated for cervical intraepithelial neoplasia grade 2 or greater (CIN2+) and for CIN3+ histology, and the differences were compared with the sensitivity and specificity of the original cytologic interpretation using cutoffs of atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesion (LSIL). RESULTS: With the endpoint of CIN2+ histology, the difference in sensitivity between external experts and the original interpretation was -5.3 (95% confidence interval [CI], -16.0 to 5.4) with ASCUS as the cutoff and 3.8 (95% CI, -8.2 to 15.8) with LSIL as the cutoff. External experts had slightly lower specificity using ASCUS as the cutoff (-3.4; 95% CI, -3.9 to -2.9) and LSIL as the cutoff (-0.7; 95% CI, -1.0 to -0.4). CONCLUSIONS: The accuracy of the external experts' interpretation was similar to that of the original interpretation. Therefore, the current results indicated that LBC is not expected to increase sensitivity even if it is used by interpreters who have extensive experience with this technique.

Assessment of specimen adequacy reproducibility: an Italian experience.

Interobserver disagreement on smear adequacy may influence the evaluation of the performance of samplers as well as Pap test sensitivity and follow-up. In 1998, the Italian Group for Cervical Cancer Screening (GISCi) promoted a study on the reproducibility of adequacy criteria using a modified version of the Bethesda system. A set of 200 smears was circulated among six Italian laboratories situated in different parts of the country. For each smear, participants were requested to provide a summary judgment on its adequacy and on the cause(s) of inadequacy, if any. Agreement was measured using kappa-type statistics. The agreement among laboratories was generally good. In comparisons, among five laboratories, kappa values ranged from 0.47 to 0.66. At the consensus meeting on 42 slides, on which at least 2 laboratories dissented from the majority, agreement was reached unanimously for 31 reviewed slides and among 5-6 centers for 11. In this article, some guidance is given in order to attribute to one of the two categories satisfactory/unsatisfactory those smears that have been traditionally considered as candidates for the category of "satisfactory but limited by em leader " (SBLB). New Italian guidelines on adequacy proposed the GISCi are presented and the recommendation is made to eliminate the SBLB category.

Impact of the AutoPap (currently Focalpoint) primary screening system location guide use on interpretation time and diagnosis.

BACKGROUND: AutoPap (currently Focalpoint) is a computerized scanning system for the primary screening of cervicovaginal smears. For smears indicated to require further review, the system provides maps (PapMaps) to identify the most abnormal areas of the smear. METHODS: To study the effect of PapMaps on diagnosis, 481 smears (from 4656 successfully processed smears using AutoPap) were first classified by conventional manual interpretation and then reinterpreted blind by the same cytologist who limited his examination to only the fields of view marked by the PapMaps. The interpretation time with and without PapMaps was measured on another simple random sample of 188 smears. RESULTS: The interpretation time was reduced significantly, by approximately 40% using PapMaps (average reduction, 136 seconds per smear, 95% confidence interval [CI], 123-150). No cases manually classified as low-grade squamous intraepithelial lesions (LSIL) or worse and 20% of those manually classified as atypical squamous cells of undertermined significance (ASCUS) were judged as completely normal on the basis of fields of visions marked by PapMaps. In none of the latter was a histologically confirmed intraepithelial lesion identified. In relation to detailed diagnosis, the weighted kappa between manual and PapMap-aided interpretation was 0.745 (95% CI 0.687-0.804). Systematic differences were found (symmetry chi-square(10d.f) =19.11, P = 0.039): 48% of smears classified as ASCUS and 23% classified as LSIL by conventional diagnosis were classified as less severe (including normal) on the basis of PapMaps. CONCLUSIONS: Use of PapMaps resulted in a substantial reduction in interpretation time. PapMaps showed good sensitivity (100% for squamous intraepithelial lesions and 80% for ACSUC) for selecting abnormal slides. The latter require full examination: detailed diagnosis based only on areas marked by PapMaps could lead to under-grading.