Performance of ThinPrep liquid-based cervical cytology in comparison with conventionally prepared Papanicolaou smears: a quantitative survey

Efficiency of an inexpensive liquid-based cytology performed by cytocentrifugations: a comparative study using the histology as reference standard

BACKGROUND

Although liquid-based cytology (LBC) is now recommended for cervical cancer screening, it requires expensive automated devices and materials. To evaluate the efficiency of inexpensive LBC methods relying on an inexpensive fixative liquid, Easyfix, we compared the results obtained by the liquid-based cytology (LBC) diagnoses performed by cytocentrifugations (Papspin and Turbitec) with those obtained by histology. Furthermore, we evaluated the efficiency of the fixative liquid, Easyfix, to preserve HPV DNA in the collected samples.

METHOD

266 LBC were compared with 174 colposcopies and 91 Loop Electrosurgical Excision Procedure (LEEP). Among the LBC, 51 were performed using the Papspin system and 215 were performed using the Turbitec system. To control the quality of the preservation liquid, Easyfix, we correlated the results of HCII assays with those of HPV PCR.

RESULTS

For Papspin and Turbitec systems, the sensitivities were respectively 82.6% (95% CI: 61.2-95.0%, p < 0.001) and 75.0% (95% CI: 64.4-89.8%, p < 0.001) and the specificities were 92.6% (95%CI: 76.5-99.1%, p < 0.001) and 96.2% (95% CI: 91.3-98.7%, p < 0.001). We find no statistical difference between the results of the both systems (p = ns). The sensitivity of the HCII was 86.4% (95% IC: 77.4-92.8%, p < 0.001) and the specificity was 39.4% (95% CI: 31.2-48.1%, p < 0.001). The comparison between HCII and HPV-PCR shows a good correlation: the kappa was 0.89.

CONCLUSION

LBC performed by cytocentrifugations are inexpensive, reduce inadequate smears, show excellent efficiency and allow HPV detection by molecular biology.

An alternative cost effectiveness analysis of ThinPrep in the Australian setting

OBJECTIVE

To assess the clinical and economic impacts of the use of liquid based cytology (LBC) in the Australian average risk population from the perspective of the public health care budget.

BACKGROUND

Concerns over the evaluation of medical technologies in Australia, which are assessed by the Medicare Services Advisory Committee (MSAC), have been raised recently. We report on the evaluation of LBC, which although being widely adopted in other parts of the world, has, despite substantial uptake in the private sector in Australia, been rejected for public funding by MSAC.

METHODS

We used the health economic model developed by MSAC, but populated the model with the best available international data, sourced from a published review article. The economic model considered the clinical benefits and the costs arising from a biennial cervical screening programme. Net costs divided by life years saved is the cost per life year saved and this is reported as the incremental cost effectiveness.

RESULTS

Populating the MSAC model with data on test performance showed that one type of LBC (ThinPrep) 'dominates' the conventional Pap smear in the screening of average risk women in the Australian setting.

CONCLUSION

The health economic model created by MSAC predicts that ThinPrep dominates the conventional Pap as a screening test for cervical cancer. An additional 2240 high-grade lesions could be detected, resulting in 480 life years gained and delivering an expected saving to the health care system of $5,536,000 per annum if liquid based cytology replaced the conventional Pap.

DCS liquid-based system is more effective than conventional smears to diagnosis of cervical lesions

OBJECTIVE

To compare the performances of Papanicolaou test (PapTest) and of a new liquid-based cytology method, DNA-Citoliq System (DCS), in a high-risk population, with histology confirmation.

METHODS

Paired specimens of exfoliated cervical cells were collected under split-sample protocol. All patients were submitted to colposcopy and a biopsy taken when any atypical transformation zone was seen. Sensitivity, specificity, positive and negative predictive values, and overall accuracy of both conventional and DCS methods were computed in relation to histology.

RESULTS

A total of 1095 patients were analyzed by two cytology methods and, in 425 (38.8%), histologically. There were significantly more adequate samples with DCS (98.63%) than with conventional (89.6%) smears (P < 0.001). ASCUS was diagnosed significantly more with DCS than with conventional Pap (P < 0.001). Conventional Pap misclassified as normal 55.4% (158/285) of cases with either LSIL or HSIL or cancer at histology, whereas DCS misclassified 31.2% (89/285) of cases (P < 0.001). DCS had a significantly higher sensitivity (70% and 91.3%) than the conventional Pap (49.8% and 72.8%) to detect both LSIL+ and HSIL+ at histology, respectively. On the other hand, specificity of conventional smear (88.2% and 85.2%) was significantly higher than DCS (75.4% and 70.9%) considering both LSIL+ and HSIL+ at histology, respectively.

CONCLUSIONS

This study confirms the superiority of the liquid-based cytology system DCS to detect cervical lesions. The rate of adequate DSC slides was significantly higher than with conventional cytology.

Dysplasia associated with atypical glandular cells on cervical cytology

OBJECTIVES

To estimate the rates of and identify risk factors for disease in women with atypical glandular cells of undetermined significance (AGUS).

METHODS

From 1998-2001, 477 Pap tests at Hartford Hospital were classified as AGUS and met the inclusion criteria of this study. Findings were evaluated for 2 years from the initial test. Disease was defined as histology results with a finding of high-grade squamous intraepithelial lesion or greater.

RESULTS

Disease was diagnosed in 9% of the women, including malignancy in 3%. Women with malignant-appearing AGUS Pap tests had a higher rate of disease (29%) than women with benign-appearing (5%, P < .01) and unspecified AGUS Pap tests (13%, P < .03). Malignancies were associated with all subclassifications of AGUS Pap tests. Women aged less than 35 years were more likely to have disease than women aged 35 years or older (P < .02). Most women aged younger than 35 years had a squamous abnormality, whereas women aged 35 years or older had a greater diversity of squamous and glandular lesions and accounted for all cases of endometrial cancer, adenocarcinoma in situ, and cervical adenocarcinoma. Women with persistent AGUS Pap tests had a 31% rate of disease. The rate of disease among women with AGUS Pap tests collected by liquid-based cytology was 11%, compared with 6% among samples collected by the conventional method.

CONCLUSION

These data suggest that women with atypical glandular cells are at substantial risk for dysplasia and malignancy. The rate of disease varies with the method of Pap test collection, age, presence of persistent AGUS Pap tests, and AGUS subclassification.

Resolving ASCUS without recourse to HPV testing: Manual reprocessing of residual automated liquid-based cytology (ALBC) material using manual liquid-based cytology (MLBC)

We show that residual cell material from ThinPrep PapTest (Cytyc Corporation, Boxborough, MA) atypical squamous-cells of undetermined significance (ASCUS) cases may be manually reprocessed to triage women into actionable diagnostic categories (HSIL, LSIL, and Negative). Material remaining from each of 358 ThinPrep ASCUS cases was manually reprocessed as two slides, labeled "A" and "B." Interobserver agreement between case contributors (CCs) and three sequential reviewers (SRs) was analyzed with 186 cases (Study 1), and diagnostic reproducibility between SRs was examined with an additional 172 cases (Study 2). In Study 1, CCs classified 33% of cases as LSIL or greater, SRs classified 60% as LSIL or greater, and there was 58% diagnostic agreement between CCs and SRs. No "Negative" case assignment by one group afforded an "HSIL" assignment by the complementary group. In Study 2, there was 95% agreement between SRs A slide and B slide diagnoses with 54% of A slides and 55% of B slides classified as LISL or greater. Again, no "Negative" case assignment to one slide afforded an "HSIL" assignment to the complementary slide. Overall, 12.6% of the 358 cases showed HSIL, and all HSILs by one observer group were ASCUS or greater by the complementary observer group. Using manual reprocessing beyond the 21-day specimen outdate for HPV testing by the Hybrid Capture II High Risk HPV test (HR-HCII; Digene Corporation, Beltsville, MD), many ThinPrep ASCUS cases were reclassified as LSIL or HSIL. The 12.6% HSIL proportion of this study approximated the 11.5% CIN 2 or greater proportion of the ALTS ASCUS arm. Similar to ALTS, manual liquid-based cytology (MLBC) would have referred nearly 60% of women to colposcopy for a definitive diagnosis of HSIL or LSIL without resorting to HPV testing. These data demonstrate that many cases of automated liquid-based cytology (ALBC)-diagnosed ASCUS represent unrecognized SIL, which is present in the ALBC specimen vial at the time the ASCUS diagnosis is rendered.

DNA methylation profiling of cervical squamous intraepithelial lesions using liquid-based cytology specimens: an approach that utilizes receiver-operating characteristic analysis

BACKGROUND

Cervical carcinoma is a common malignancy among women worldwide, and its pathogenesis is related causally to human papillomavirus infection. The progression from precursor squamous intraepithelial lesions to cervical carcinoma requires additional genetic and epigenetic alterations that have not been characterized fully. The authors examined aberrant promoter methylation of multiple tumor suppressor genes in precursor squamous intraepithelial lesions.

METHODS

A multiplex, nested, methylation-specific polymerase chain reaction approach was used to examine promoter methylation of 15 tumor suppressor genes in high-grade squamous intraepithelial lesions (HSIL, n = 11), low-grade squamous intraepithelial lesions (LSIL, n = 17), and negative tissues (n = 11) from liquid-based cytology samples. The area under the receiver-operating characteristic (ROC) curve was determined for individual methylated tumor suppressor genes and for gene combinations to evaluate test performance for the ability of methylation profiles to distinguish HSIL cytology samples from combined LSIL/negative cytology samples.

RESULTS

Aberrant promoter methylation of DAPK1 and IGSF4 occurred at a high frequency in HSIL samples and was absent in LSIL and negative samples. There was a significant trend toward increased methylation with the increased severity of lesions, and the mean number of methylated genes was significantly higher in HSIL samples compared with LSIL and negative samples. Using the area under the ROC curve as a measure of test performance, the methylation of IGSF4 and DAPK1 had areas that were significantly greater than 0.5; thus, each had the ability to distinguish HSIL samples from combined LSIL/negative samples. The areas under the curve for the best two-gene combination (IGSF4/DAPK1) and the best three-gene combination (IGSF4/DAPK1/HIC1) were not statistically different from the best individual tumor suppressor gene (IGSF4) in distinguishing HSIL samples from combined LSIL/negative samples.

CONCLUSIONS

Aberrant promoter methylation of tumor suppressor genes is an epigenetic alteration that occurs during neoplastic progression to cervical carcinoma. The methylation status of multiple tumor suppressor genes can be evaluated using ROC analysis to determine methylation profiles that can distinguish HSIL samples from combined LSIL/negative samples.

Evidence Supporting the Current Management Guidelines for High-Grade Squamous Intraepithelial Lesion Cytology

OBJECTIVE

The study was undertaken to provide consensus guidelines for the management of women with a cytologic interpretation of high-grade squamous intraepithelial lesion (HSIL) on cytologic examination. This review article presents relevant literature supporting the proposed guidelines.

PARTICIPANTS

An independent panel of 121 experts in various aspects of the diagnosis and management of cervical cancer precursors, including representatives from 29 participating professional organizations, federal agencies, national and international health organizations, and others were invited by the American Society for Colposcopy and Cervical Pathology.

CONSENSUS PROCESS

Guidelines for the management of women with HSIL cytologic results were developed through a multistep process. Draft management guidelines were developed by the HSIL working group after formal literature reviews and obtained input from the professional community at large by way of an interactive internet-based bulletin board. At the American Society for Colposcopy and Cervical Pathology Consensus Conference, September 6 through 8, 2001, in Bethesda, Maryland, the guidelines were discussed, revised, and adopted by formal vote.

CONCLUSIONS

Evidence-based guidelines have been developed for the management of women with HSIL cytologic results.

High-Grade Squamous Intraepithelial Lesions: Abbreviating Posttreatment Surveillance

OBJECTIVE

To evaluate whether the surveillance schedule for patients treated with loop excision for high-grade squamous intraepithelial lesions could be improved.

METHODS

Women treated in our dysplasia clinic for high-grade squamous intraepithelial lesions by loop excision between January 1990 and December 1999 were identified. Demographic information, pathologic diagnosis, and follow-up visits were extracted from medical records. Follow-up data included all Papanicolaou (Pap) tests and/or cervical biopsies performed in our clinic after the initial procedure.

RESULTS

Women (n = 705) were treated for biopsy-proven high-grade dysplasia. Of those treated, 526 (74%) had at least 1 follow-up Pap test performed in our clinics within 2 years of their original procedure. During the 2 years of posttreatment surveillance, 70 (13.3%) women demonstrated recurrent cervical intraepithelial neoplasia 2 or 3. Recurrence was highest during the first 6 months and between months 22 and 24 of surveillance. This rate was noted to be dramatically lower during months 7 to 21 of surveillance (P <.001). Increasing age was independently associated with a 1.6-fold per decade (95% confidence interval 1.29, 1.9) increase in risk of recurrence. A negative margin status was independently associated with a 0.29-fold (95% confidence interval 0.17, 0.5) decrease in risk of recurrence. Race was not shown to have an influence on risk of recurrence.

CONCLUSION

A clinically and financially optimal surveillance schedule for women treated for high-grade dysplasia with loop excision would be to obtain Pap tests every 6 months for 1 year and then return to annual screening. Lengthening the surveillance intervals could be beneficial to patients, while decreasing healthcare costs, without compromising the ability to detect and treat recurrent disease.

LEVEL OF EVIDENCE

II-2