ThinPrep Processor. Clinical trials demonstrate an increased detection rate of abnormal cervical cytologic specimens

Computational Cytology: Lessons Learned from Pap Test Computer-Assisted Screening

BACKGROUND

In the face of rapid technological advances in computational cytology including artificial intelligence (AI), optimization of its application to clinical practice would benefit from reflection on the lessons learned from the decades-long journey in the development of computer-assisted Pap test screening.

SUMMARY

The initial driving force for automated screening in cytology was the overwhelming number of Pap tests requiring manual screening, leading to workflow backlogs and incorrect diagnoses. Several companies invested resources to address these concerns utilizing different specimen processing techniques and imaging systems. However, not all companies were commercially prosperous. Successful implementation of this new technology required viable use cases, improved clinical outcomes, and an acceptable means of integration into the daily workflow of cytopathology laboratories. Several factors including supply and demand, Food and Drug Administration (FDA) oversight, reimbursement, overcoming learning curves and workflow changes associated with the adoption of new technology, and cytologist apprehension, played a significant role in either promoting or preventing the widespread adoption of automated screening technologies. Key Messages: Any change in health care, particularly those involving new technology that impacts clinical workflow, is bound to have its successes and failures. However, perseverance through learning curves, optimizing workflow processes, improvements in diagnostic accuracy, and regulatory and financial approval can facilitate widespread adoption of these technologies. Given their history with successfully implementing automated Pap test screening, cytologists are uniquely positioned to not only help with the development of AI technology for other areas of pathology, but also to guide how they are utilized, regulated, and managed.

Comparable performance of conventional and liquid-based cytology in diagnosing anal intraepithelial neoplasia in HIV-infected and -uninfected Thai men who have sex with men

BACKGROUND

Anal cytology has increasingly been used to screen for anal intraepithelial neoplasia (AIN) among men who have sex with men (MSM) at increased risk for anal cancer. Use of liquid-based cytology has been reported to reduce fecal and bacterial contamination and air-drying artifact compared with conventional cytology. Costs associated with liquid-based cytology, however, may limit its use in resource-limited settings.

METHODS

Anal swab samples were collected from MSM participants and used to prepare conventional and liquid-based cytology slides. Abnormal conventional cytology results triggered referral for high-resolution anoscopy and biopsy. Agreement between the 2 cytology techniques and the positive predictive value ratios of histology confirmed AIN were calculated.

RESULTS

Among 173 MSM, abnormal anal cytology was identified in 46.2% of conventional and 32.4% of liquid-based slides. The results agreed in 62.4% of cases with a κ value of 0.49 (P < 0.001). HIV-infected MSM had a 3.6-fold increased odds of having discordant anal cytology results (95% confidence interval: 1.6 to 7.8; P = 0.001) compared with HIV-uninfected MSM. Histological AIN 2 and 3 were identified in 20 MSM. The positive predictive value ratios and 95% confidence interval indicated no difference between the 2 techniques.

CONCLUSIONS

Conventional anal cytology may be a preferred option for resource-limited settings given comparable performances to liquid-based cytology for the detection of AIN, although the agreement between the 2 techniques was lower among HIV-infected MSM. Due to high prevalence of abnormal anal cytology and AIN, health systems should prepare adequate infrastructure for high-resolution anoscopy services and AIN treatment.

[Comparison of the ThinPrep monolayer technique and conventional cervical Pap smears in a high-risk population using the Munich II nomenclature]

OBJECTIVE

In this prospective study using the Munich II nomenclature for cervical cytology. Pap smear results obtained by the ThinPrep monolayer technique and those obtained by the conventional method were compared.

METHODS

Pap smears were obtained from 1,000 women using an Ayre spatula/endocervical brush combination. Following transfer of the cell sample onto a slide, the same collection devices were rinsed in a liquid medium and processed using ThinPrep-2000 processor (split-sample technique).

RESULTS

Specimen inadequacies due to drying artefacts, cell overlap or low number of epithelial cells were rare with both methods without any significant differences. However, ThinPrep slides were significantly less often compromised by red or white blood cells or by cytolysis. In contrast, endocervical cells were missing in 11.6% of slides compared to only 2.3% in conventional Pap smears. ThinPrep yielded results of unknown significance (Pap III) significantly less often (4.2 vs 6.3%).

CONCLUSIONS

ThinPrep slides are less frequently compromised by blood components or cytolysis. Inconclusive results of Pap III are slightly less frequent when using ThinPrep. However, there is a significant percentage of slides lacking the endocervical component. Using a combination of spatula and cytobrush, this may not necessarily be due to non-representative cell sampling.

Randomized Pilot Study Comparing Rates of Endocervical Cell Recovery between Conventional Pap Smears and Liquid-Based Cytology in a Pregnant Population

OBJECTIVE.: To determine whether liquid-based cytology improves Pap smear adequacy, as defined by the presence of endocervical cells, compared with conventional cytology during pregnancy. MATERIALS AND METHODS.: A randomized pilot study was conducted between May 2001 and May 2002. Patients presenting for their first prenatal visit were randomized to receive either a conventional Pap smear or a liquid-based smear (ThinPrep). Rates of endocervical cell recovery and cytologic results were compared between the groups. RESULTS.: Eighty-one patients were enrolled in the study. There were no differences between the groups in age (p = .40), parity (p = .62), gestational age (p = .14), history of abnormal pap (p = .08), previous treatment of neoplasia (p = 1.00), and tobacco use (p = .67). Adequacy of the standard pap versus the liquid-based smear was not different between the two groups (90.5% vs 82.1%, respectively;p = .34). CONCLUSIONS.: The results of this pilot study show that rates of endocervical cell recovery in a pregnant population are not statistically different using conventional or liquid-based cytology. Further research is indicated to assess the utility of the more expensive ThinPrep technology in this population.

Effect of study design and quality on unsatisfactory rates, cytology classifications, and accuracy in liquid-based versus conventional cervical cytology: a systematic review

BACKGROUND

Liquid-based cytology is reported to increase the sensitivity of cervical cytology and the proportion of slides that are satisfactory for assessment, in comparison with conventional cytology. Although some countries have changed to liquid-based cytology for cervical screening, controversy remains. We reviewed the published work to assess the performance of liquid-based cytology relative to conventional cytology in primary studies assessed to be of low, medium, or high methodological quality.

METHODS

56 primary studies were reviewed and assessed with strict methodological criteria. Liquid-based cytology and conventional cytology were compared in terms of the percentage of slides classified as unsatisfactory, the percentage of slides classified in each cytology category, and the accuracy of detection of high-grade disease. Data were examined for studies overall and in strata to examine the effect of study quality on results.

FINDINGS

The median difference in the percentage of unsatisfactory slides between liquid-based cytology and conventional cytology was 0.17%. Only one small study was a randomised controlled trial. The classification of high-grade squamous epithelial lesion varied according to study quality (p=0.04), with conventional cytology classifying more slides in this category than did liquid-based cytology in high-quality studies (n=3) only. In medium-quality (n=30) and high-quality studies, liquid-based cytology classified more slides as atypical squamous cells of unknown significance than did conventional cytology when compared with low-quality studies (n=17; p=0.05). Only four studies provided sufficient verified data to allow estimation of sensitivity and specificity and comparison of test accuracy.

INTERPRETATION

We saw no evidence that liquid-based cytology reduced the proportion of unsatisfactory slides, or detected more high-grade lesions in high-quality studies, than conventional cytology. This review does not lend support to claims of better performance by liquid-based cytology. Large randomised controlled trials are needed.

The comparative diagnostic accuracy of conventional and liquid-based cytology in a colposcopic setting

OBJECTIVE

This study was conducted to compare the performance of liquid-based cytology (LBC) and conventional cytology (CS) in the high prevalence setting of colposcopy clinic.

DESIGN

A split sample of matched ThinPrep (TP) and conventional smear from 563 patients were evaluated blindly. The performance of both techniques was compared with the gold standard of biopsy results or normal colposcopy examination in 441 cases.

SETTING

Colposcopy clinic of an inner city hospital for women and children.

SAMPLE

Five hundred and sixty-three women referred to colposcopy clinic over 14-month period.

METHODS

Cervical smears were taken from 563 women referred for colposcopy. Using the split-sample technique, the material was spread on a conventional (CS) slide and the remaining material rinsed in a PreservCyt solution. A T2000 processor was used to prepare LBC preparations. All women underwent colposcopy/biopsy according to local protocol. Four hundred and forty-one women met the diagnostic standard criteria of the study, which was either a normal colposcopy or histopathology result. Sensitivity, specificity and positive and negative predictive values were calculated for both methods of cytology preparations.

MAIN OUTCOME MEASURES

Matched TP and conventional smears, detection of abnormality, matched biopsies, sensitivity, specificity, and positive and negative predictive values.

RESULTS

Inadequate rates for CS and LBC (TP) were 4.3% and 0.68%, respectively. In 73% of cases, the CS and the LBC preparations showed exact agreement, whereas 77% agreement was seen when comparison was made for amalgamated low grade and high grade abnormalities. Low grade cytological abnormalities accounted for 44% of LBC slides versus 37% in CS slides. High grade cytological abnormalities accounted for 22% of LBC versus 17% seen in CS cases (P < 0.001). LBC showed increased sensitivity in the detection of CIN2 or worse than CS (92% and 83%, respectively) and CS showed greater specificity than LBC (82% and 76%, respectively).

CONCLUSIONS

In high prevalence setting, LBC performed at least as well as CS. The inadequate rate was significantly lower with LBC. The numbers are too small, however, to make confident comments about increased sensitivity and negative predictive value with LBC. Larger studies are required to verify these findings.

Comparison of ThinPrep and conventional preparations in pancreatic fine-needle aspiration biopsy

Use of ThinPrep preparation for fine-needle aspiration biopsy (FNA) is gaining popularity. However, there may be a difference in the morphology and the operating characteristics between ThinPrep and conventional methods. The objective of this study was to compare the accuracy of the two methods and to address the pitfalls of ThinPrep preparation in pancreatic FNA. A computer search identified 67 pancreatic FNAs with both conventional smears and ThinPrep preparation during a 19-mo period. These cases, obtained under endoscopic ultrasound-guidance, consisted of 47 malignant neoplasms (44 ductal carcinomas, two mucinous neoplasms, and one islet cell tumor) and 20 benign lesions. Direct smears were prepared first and the remaining material was then put into PreservCyt Solution for ThinPrep slides. All slides were reviewed and the cytologic diagnoses were correlated with histologic and clinical follow-up. Five conventional and 16 ThinPrep specimens were unsatisfactory due to insufficient cellularity. These cases were excluded from the analysis. Among the 62 cases evaluated by conventional preparation, 77% (34) were diagnosed as positive and 14% (seven) atypical/suspicious by conventional smears. For the 51 ThinPrep specimens, 58% (22) were interpreted as positive and 31% (12) atypical/suspicious. The sensitivity, specificity, and accuracy of diagnosing a malignancy were 77%, 100%, and 84% for conventional smears and 58%, 100%, and 67% for ThinPrep preparation, respectively. There were no false positives with either method. However, three benign lesions were interpreted as atypical/suspicious with ThinPrep preparation because of the presence of single atypical cells with distinct nucleoli. One of the two mucinous neoplasms was incorrectly diagnosed with ThinPrep preparation because of lack of mucin. The diagnostic accuracy of pancreatic FNA using ThinPrep is inferior to that of conventional smears. This may be partly due to the use of split sample technique resulting in scant cellularity in ThinPrep preparation and partly due to the differences in morphology between the two preparations. Therefore, the current morphologic criteria may need modification for ThinPrep preparation in pancreatic FNA.

Comparison of Performance of Conventional and ThinPrep Gynecologic Preparations in the College of American Pathologists Gynecologic Cytology Program

Context.—Results of clinical trials suggest that interpretation of liquid-based cytology preparations is more accurate and is associated with less screening error than interpretation of conventional preparations.

Objective.—In this study, the performance of participants in interpreting ThinPrep (TP) preparations was compared with participants' performance on conventional Papanicolaou tests in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology (PAP).

Design.—The results of the PAP from the year 2002 were reviewed, and the discordancies to series and exact-match error rates for the 2 cytologic methods were compared.

Results.—For this study, a total of 89 815 interpretations from conventional smears and 20 886 interpretations from TP samples were analyzed. Overall, interpretations of TP preparations had both significantly fewer false-positive (1.6%) and false-negative (1.3%) rates than those of conventional smears (P = .001 and P = .02, respectively) for validated or validated-equivalent slides, as assessed by concordance with the correct diagnostic series. In this assessment of concordance to series, interpretations of educational TP and conventional preparations were similar, except for high-grade squamous intraepithelial lesion, in which the performance was significantly worse for educational TP preparations (false-negative rate of 8.1% vs 4.1% for conventional smears, P &lt; .001). When interpretations were matched to the exact diagnosis, validated-equivalent TP preparations were generally more accurate for diagnoses in the 100 series and 200 series than were conventional smears. Notably, for the reference diagnosis of squamous cell carcinoma, the exact-match error rate on validated equivalent TP slides was significantly greater than that of conventional slides (44.5% vs 23.1%, P &lt; .001). Interpretations of educational TP preparations also had a significantly higher error rate in matching to the exact reference diagnosis for squamous cell carcinoma (33.7% vs 22.8%, P = .007).

Conclusions.—Overall, TP preparations in this program were associated with significantly lower error rates than conventional smears for both validated and educational cases. However, unlike the negative for intraepithelial lesion and malignancy, not otherwise specified, low-grade squamous intraepithelial lesion, and adenocarcinoma cytodiagnostic challenges, participants' responses indicated some difficulty in recognizing high-grade squamous intraepithelial lesion and squamous cell carcinoma.

Atypical glandular cells?an update

The diagnostic category of atypical glandular cells (AGC) in the Bethesda system for the reporting of cervicovaginal cytology has undergone significant modification since its inception in 1988. More than a decade later, this category remains a diagnostic challenge to both clinicians and cytopathologists because of the lack of uniform cytologic criteria, the lack of interobserver agreement in the diagnosis, and the lack of standardized patient management guidelines. This article reviews the current classification of AGC in the Bethesda system, the cytomorphologic features and differential diagnosis, the clinical significance of a diagnosis of AGC, and the clinical management of patients with AGC. This article provides a comprehensive clinicopathologic review of the category of AGC.

Liquid-based cytology and conventional cervical smears

BACKGROUND

This study compared the findings of cervical cytology screening by ThinPrep Papanicolaou (Pap) tests (TP) with the findings of screening by conventional cervical smears (CS) in a screening population involving what to the authors' knowledge is the largest sample of ThinPrep Pap tests published to date.

METHOD

Data from 191,581 CS that were screened in the period from March 1, 1998 to February 28, 2000 were compared with data from 190,667 TP performed from March 1, 2000 to February 28, 2002 and that were obtained from the same sources.

RESULTS

With TP, the unsatisfactory rate was reduced from 0.48% to 0.32%. Fewer cases were considered to be suboptimal (19.12% vs. 12.97%). The detection rates of squamous cell carcinomas, adenocarcinomas, and high-grade squamous intraepithelial lesions (HSIL) were essentially unchanged in the TP group (0.005%, 0.003%, and 0.25%, respectively) compared with the rates for the CS group (0.01%, 0.006%, and 0.25%, respectively). There was an increase in the detection of atypical squamous cells of undetermined significance (ASCUS; 3.74% vs. 3.19%) and low-grade SIL (LSIL; 1.67% vs. 1.01%) with a decrease in the ASCUS-to-LSIL ratio from 3.15 for CS to 2.33 for TP. The detection of atypical glandular cells of undetermined significance (AGUS) increased slightly from 0.07% to 0.09%. The proportion of cells reported to have reactive atypia dropped from 2.71% to 1.48%. Limited biopsy correlation (range, 73.2-76.2%) confirmed the increased sensitivity of TP. More actinomyces (1.07% vs. 0.52%) were detected in TP samples despite of a similar portion of intrauterine-device users. The average primary screening and rapid rescreening time of each slide were reduced from 8 minutes to 4 minutes and from 2 minutes to less than 1 minute, respectively.

CONCLUSIONS

The preliminary experience of the authors of the current study appears to support the use of the ThinPrep Pap test to enhance the efficiency of cervical cytology screening.

Atypical glandular cells

The 2001 Bethesda System has radically altered the classification of glandular abnormalities. The recognition of the cytologic features of atypical glandular cells on cervicovaginal smears is important because a significant number of patients will be found to have an underlying cancerous or dysplastic lesion of the exocervix, endocervix, or endometrium. The differential diagnosis of AGC on cytology is diverse and accurate classification is necessary because the most appropriate form of follow-up depends on the specific subcategorization of the atypical glandular cells. Because the level of interobserver agreement in the diagnosis of AGC is poor, effective communication between cytopathologists and clinicians is essential to accurately triage these patients. This article should help the cytology practitioner by providing a comprehensive review of the approach to the interpretation, clinical significance, histopathologic correlation, and management of patients who have atypical glandular cells on gynecologic cytology specimens.

Molecular markers in cervical cytology

It is expected that in the near future, the high sensitivity of array-based technologies and identification of panels of molecular fingerprints that are specific for each disease process will allow the pathologist to analyze cytologic samples and tissue biopsies by these technologies in conjunction with morphologic evaluation. This approach could lead to a new era in diagnosis and patient management, where each patient may receive individualized treatment according to the molecular characteristics of the disease that are obtained from a minute amount of tissue. Therefore, it is important for pathologists and other clinical specialists to have an understanding of these molecular technologies. It is hoped that this article will allow practitioners to incorporate these concepts into their training, and, eventually, into their daily practice.

Use of ThinPrep monolayer technique and cytospin preparation in urine cytology: a comparative analysis

We compared the ThinPrep (TP) technique to the cytospin (CS) preparation in the cytological diagnosis of urine by processing 79 specimens by these two techniques. Ten cases were positive for malignancy (six high grade (HG)/carcinoma in situ; four low grade (LG) transitional cell carcinomas (TCC)). Forty-eight cases were within normal limits (59%) and 21 cases had atypical cytological features (19%). The TP technique was better in terms of a cleaner background with fewer obscuring inflammatory cells and blood and with a more even distribution of cells. In general, the cytomorphology was comparable in both techniques. However, in cases with malignancy, CS was relatively superior in the cytomorphologic details; in TP, the diagnostic cells were mostly dispersed as single cells with loss of architectural features and were difficult to find. Artifactual empty spaces and air-drying were more frequently present in TP. In cases contaminated with squamous cells, the urothelial cells were difficult to find in TP. Screening time was comparable for both techniques. In conclusion, to avoid false-negative diagnosis, CS would be complementary to the TP technique in malignant cases and, in particular, those with low cellularity.

Development of an automated extraction procedure for detection of human papillomavirus DNA in liquid based cytology samples

Liquid based cytology samples are being used increasingly to improve cervical screening and have the advantage that residual cell suspension is available for other tests such as human papillomavirus (HPV) detection. However, as the transport medium is optimised for downstream cytology, problems can be experienced during extraction of nucleic acid. This study aimed to develop a robust protocol for automated extraction of HPV DNA from cervical, liquid based cytology samples using a high throughput robotic system. Considerable modification of existing clinical extraction protocols for swab specimens, together with optimisation of required sample input volume was required to reduce sample blockage during the extraction to acceptable levels. The blockage rate and optimal processing volume was assessed by extracting a fixed volume (1/4) of re-suspended material from the centrifuged pellets of 10, 5 and 1 ml aliquots of 200 specimens. Analysis revealed 17.5% blockage with specimens originating from 10 ml aliquots; 3% with 5 ml and no blockage with 1 ml aliquots of the same samples. A 3% blockage level is acceptable for an automatic well clearance procedure to be followed. HPV testing of the extracts by real-time PCR showed a 1.5% loss of sensitivity in extracts originating from 1 ml aliquots as compared with 5 ml aliquots with a consequent loss of detectable HPV genotypes after reverse hybridisation. In short, 5 ml of liquid based cytology specimen is recommended for nucleic acid extraction, to allow optimal detection of HPV types in clinical samples while retaining maximum efficiency of the robotic extraction procedure.

Paying for prevention standardizing the measurement of the value of health care interventions

It is not clear if spending more on tests that enhance the accuracy of Pap smears would lead to a greater reduction in cancer incidence than if the money were spent to include a greater proportion of women in primary screening. The cost effectiveness of tests beyond the Pap smear has not been clearly demonstrated. There is the question of whether cervical cancer incidence can be decreased more by improving the tests for patients who are already screened or by improving access to the unscreened population. Cervical cancer screening represents only one of many public health issues competing for resources. Given that there are choices to be made, the optimal yardstick against which all resource-competing programs are measured should be marginal benefit versus marginal cost.

In vitro adjuncts to the pap smear

The Pap smear has been recognized widely as the most effective cancer screening test in the history of medicine. It is widely believed that the use of this test has been responsible for the drastic reduction in the incidence and mortality of cervical cancer in the United States, Canada, and much of Western Europe in the last 50 years. Several adjuncts to the Pap smear including liquid based cytology, computer-assisted screening, human papilloma virus and molecular testing are discussed.

Diagnosis of melanoma aspirates on ThinPrep: the University of Michigan experience

The purpose of this study was to compare the cytologic features of melanoma fine-needle aspirates (FNAs) prepared by ThinPrep (TP) with those in conventional smears (CS) and to identify any diagnostic pitfalls. Fifty-one aspirates diagnosed as melanoma were obtained, 36 of which were prepared by both TP and CS. The preparations were evaluated for cellularity, cell aggregates, cellular appearance, melanin pigment, cytoplasmic, and nuclear features. Categorical data were analyzed by the chi-square test and continuous data by the Wilcoxin-signed rank test. Correlation was determined by Spearman's test for bivariate correlations (rho). Good correlation between the two methods was identified for the following features: cellularity, cell type, bi/multinucleated cells, cytoplasmic features, NC ratio, and presence of macronucleoli. TP exhibits coarser chromatin compared to CS (P = 0.005). Six of 36 CS contained large cellular groups; none of the TP contained them (P = 0.018). Twenty-five of 36 CS contained intranuclear inclusions as opposed to 12/36 TP (P < 0.001). The number of inclusions was significantly reduced on TP. The amount of intracellular melanin was the same with both techniques. Background melanin was markedly reduced on TP except when either trapped by fibrin or attached to cellular clusters (P = 0.006). Background blood was also markedly reduced on TP (P < 0.005). In summary, the cytological features of TP and CS for FNA evaluation of melanoma correlate well; however, one needs to be aware of the cytologic alterations introduced by TP. TP is a sufficient preparation method in the diagnosis of melanoma FNA aspirates when performed by clinicians. It is also a useful adjunct in bloody or low-cellular aspirates, where it tends to reduce the background blood and concentrate the cells.

Comparison of ThinPrep versus conventional smear cytopreparatory techniques for fine-needle aspiration specimens of head and neck masses

OBJECTIVES

Diagnostic accuracy of the ThinPrep process (Cytyc, Boxborough, MA) was compared with that of conventional (smear) cytopreparation for fine-needle aspiration (FNA) of head and neck masses.

METHODS

In a prospective, randomized, single-blinded study, 209 patients served as their own controls and underwent 236 FNAs using ThinPrep and conventional (smear) cytopreparatory techniques.

RESULTS

ThinPrep produced less air-drying artifact and less mechanical distortion than the conventional method. The conventional technique was diagnostic in 63% of samples; the ThinPrep technique was diagnostic in 55% of samples. When all results were combined, pathologists subjectively preferred the conventional technique but accepted use of ThinPrep as the only cytopreparatory technique for most head and neck masses.

CONCLUSIONS

For adequately experienced cytopathologists, ThinPrep is acceptable for FNA of salivary masses, neck cysts, metastatic lymph nodes, and thyroid lesions. Conventional smear technique should be used for FNA of nonmetastatic lymphoid lesions. Use of ThinPrep can complement use of the conventional (smear) cytopreparatory technique when aspirate is nondiagnostic or bloody, when the patient has a blood-borne infectious disease, when the clinician is inexperienced, or when aspirate has entered the syringe.

Interobserver variability: comparison between liquid-based and conventional preparations in gynecologic cytology

BACKGROUND

Studies have shown that the ThinPrep Papanicolaou test (TP) increases the detection of epithelial cell abnormalities compared with the conventional preparation. Little is known about the interobserver variability of reporting gynecologic cytology results using the TP preparation and its comparison with results obtained using the conventional method.

METHODS

To compare the interobserver variability between the TP method and the conventional method for reporting the diagnoses of gynecologic cytology, 20 pairs of conventional and TP slides (total, 40 slides) that were prepared from split samples were evaluated blindly by 19 cytotechnologists from three different laboratories. Each reviewer was asked to categorize each slide into the following five categories: within normal limits, benign cellular changes, atypical squamous cells of undetermined significance, low-grade squamous intraepithelial lesion (LSIL), and high-grade squamous intraepithelial lesion (HSIL). For both conventional and TP preparations, interobserver variability was analyzed using Spearman rank correlation coefficients. The mean correlation coefficients (weak, 0.0-0.4; fair, 0.4-0.7; and strong, 0.7-1.0) between the TP method and the conventional method were then compared.

RESULTS

The overall interobserver agreement as well as interobserver agreement within each laboratory was good for both TP and conventional preparations. Based on the set of conventional cervical smears, only one slide that was diagnosed as HSIL had unanimous agreement; whereas, based on the set of TP slides, three slides, including two diagnosed as HSIL and one diagnosed as LSIL, had a unanimous diagnosis. The difference in the interobserver agreement between TP and conventional methods, based on comparing their mean +/- standard deviation correlation coefficients (TP method, 0.84 +/- 0.081; conventional method, 0.82 +/- 0.105; P < 0.001), was statistically significant.

CONCLUSIONS

Interobserver agreement in reporting gynecologic cytology using the TP method is good, particularly for squamous intraepithelial lesions, and appears to be superior to the conventional method.

Liquid-based cytology: is this the way forward for cervical screening?

Liquid-based cytology (LBC) is currently being marketed as an alternative methodology to replace the conventional PAP smear in cervical cytology. A substantial body of literature exists in support of LBC, some of which is at least partially sponsored by product manufacturers. The majority of published literature in support of LBC employs Bethesda reporting terminology. In this study we have analysed published raw data and presented this in NHSCSP terminology. Claims relating to sensitivity, specificity and smear adequacy have then been considered with reference to this data. Our analysis of existing data does not support the nationwide implementation of LBC at present. Further studies are recommended in order to evaluate the place of this technology within the NHSCSP.

Evaluation of thin-layer methods in urine cytology

Conventional cytospin smears prepared from urinary tract specimens were compared with two new thin layer techniques, i.e. ThinPrep and AutoCyte PREP. Cellularity, cell preservation, background features, detection rate, screening time and ease of preparation were evaluated. Thin-layer techniques when applied to urine cytology were found to improve cell yield and cell preservation, and reduce background artefact. The reporting rate for abnormal urothelial cells was comparable to conventional cytospin smears, as was screening time. Laboratory staff found the methodologies to be practicable and easily incorporated into a large routine diagnostic service. We conclude that a one-slide thin-layer urine preparation is comparable to four cytospin slides in the detection of urothelial abnormalities, and that both ThinPrep and AutoCyte PREP have comparable features.

Liquid-based cervical cytologic smear study and conventional Papanicolaou smears: a metaanalysis of prospective studies comparing cytologic diagnosis and sample adequacy

OBJECTIVE

We sought to evaluate the cytologic diagnosis and sample adequacy of the liquid-based cervical cytologic smear (ThinPrep) compared with that of the conventional Papanicolaou smear.

STUDY DESIGN

Prospective studies of ThinPrep and conventional Papanicolaou smears were analyzed for cytologic diagnosis and sample adequacy. Computerized databases, references in published studies, and index reviews published in English were used to identify direct-to-vial and split-sample clinical trials of cervical smears performed by conventional and liquid-based techniques. Only published studies that used the Bethesda system nomenclature with clearly documented outcome data were included. Each trial was assessed for the quality of its method, inclusion and exclusion criteria, adequacy of randomization, sampling protocols, definition of outcome, and statistical analyses.

RESULTS

Twenty-five studies met inclusion criteria for this review. Odds ratios with 95% confidence intervals were calculated for each outcome. Estimates of odds ratios and risk differences for dichotomous outcomes were calculated by use of random and fixed-effects models. Homogeneity was tested across the studies. Results indicate that the ThinPrep test is as good as or superior to the conventional Papanicolaou smear in diagnosing uterine cervical premalignant abnormalities. Also the ThinPrep test provides improved sample adequacy when compared with the conventional Papanicolaou test.

CONCLUSION

The ThinPrep test improved sample adequacy and led to improved diagnosis of low-grade and high-grade squamous intraepithelial lesions. However, there is no difference in the rate of atypical cells of undetermined significance diagnosis between ThinPrep and conventional smear groups. The added cost of ThinPrep cytologic screening and, hence, its cost-effectiveness are not evaluated in this study.

Cost-effectiveness of monolayers and human papillomavirus testing compared to that of conventional Papanicolaou smears for cervical cancer screening: protocol of the study of the French Society of Clinical Cytology

The French Society of Clinical Cytology is conducting a study to compare the cost-effectiveness of monolayers and human papillomavirus (HPV) testing with that of conventional Papanicolaou (Pap) smears for cervical cancer screening. The protocol of this study is presented. It includes 3,000 women who will be evaluated by the three methods (conventional Pap smears, or monolayers with or without HPV testing) and by the reference method: colposcopy followed, in cases with abnormalities, by cervical biopsy. Efficacy or performance of the methods will be compared on the basis of sensitivity. Cost comparisons and cost-effectiveness modeling will be based on the costs associated with methods themselves and also the costs of "false positives." This will require specific collection of data concerning the costs of the three methods, as these costs have not previously been accurately documented. Patient recruiting and data collection started in September 1999 and will be complete in June 2000. The first results are expected to be available in spring 2001.

Rapid real time PCR to distinguish between high risk human papillomavirus types 16 and 18

AIMS

To assess the validity and practicality of real time polymerase chain reaction (PCR) for human papillomavirus (HPV) testing in combination with liquid based cytology samples for cervical screening.

METHODS

Real time PCR using consensus (GPS+/6+) and type specific primers was developed to detect genital HPV types. This provides rapid, efficient amplification followed by denaturation of the product and computer analysis of the kinetics data that are generated. Liquid based cytology samples were obtained from patients attending routine cervical screening clinics. DNA was extracted from the residual cellular suspension after cytology using spin columns.

RESULTS

Real time PCR successfully distinguished between HPV-16 and HPV-18 on the basis of amplification with consensus primers followed by DNA melting temperature (Tm) analysis. Sensitivities of one to 10 copies of HPV-16 (mean Tm = 79.4 degrees C; 2 SD, 0.8) and four to 40 copies of HPV-18 (mean Tm = 80.4 degrees C; 2 SD, 0.4) were obtained. In a mixed population of SiHa and HeLa cells containing known copy numbers of HPV-16 and HPV-18 genomes, HPV-16 and HPV-18 products were clearly separated by Tm analysis in mixtures varying from equivalence to 111000. Together with detailed melt analysis, type specific primers from the same region of the L1 gene confirmed the differential ability of this system. The method was applied to 100 liquid based cytology samples where HPV status using conventional GP5+/6+ PCR was already known. There was 95% agreement between the methods, with 55 positives detected by conventional PCR and 59 with real time PCR. The method was then tested on 200 routine liquid based cytology samples. Approximately 10% were positive by real time PCR, most of which were classified as HPV-16 by detailed melt analysis. Thirteen (6.8%) HPV positives were identified in 189 samples showing no evidence of cervical cytological abnormality.

CONCLUSIONS

Real time PCR is a rapid, efficient method for the detection of HPV with the separation of HPV-16 and HPV-18 on the basis of differential Tm. Preliminary results suggest it could prove

Diagnostic value of liquid-based (Thinprep) preparations in nongynecologic cases

Most studies utilizing the liquid-based ThinPrep method for the preparation of nongynecological specimens report a diagnostic sensitivity and specificity of over 90%. ThinPrep-processed slides in 162 cases sent to us from outside laboratories were assessed for their diagnostic value. These included fine-needle aspiration (FNA) (128) and other nongynecological specimens (34), representing bronchopulmomary washings, body cavity fluids, and urine samples. Slides were examined independently for adequacy and diagnostic value. These results were compared with the final diagnosis rendered upon examination of the entire submitted cytologic specimens, including direct smears, cytospins, and cell blocks. Based on review of the ThinPrep-processed slides alone, diagnosis of malignancy or neoplasia was made in 54 of 86 cases (63%), while 18/86 (21%) were less than optimal and 14/86 (16%) were unsatisfactory. Pulmonary specimens, body cavity fluids, and urine were generally satisfactory, while thyroid and breast FNA were more often less than optimal or unsatisfactory. This limited study suggests that utilization of ThinPrep processing alone may have reduced diagnostic value in the fine-needle aspiration cases studied here.

ThinPrep Pap Test promotes detection of glandular lesions of the endocervix

The objectives of this study were to evaluate 1) the detection rate of atypical glandular cells of undetermined significance of endocervical cell type (AGUS-EC) and 2) the correlation between AGUS-EC on cytology and biopsy results using the conventional Papanicolaou (Pap) smear test vs. the ThinPrep Pap test (TPPT). Cervical-vaginal samples processed by the conventional Pap smear for 11 mo in 1996-1997 were identified, as were TPPTs collected for the same interval in 1997-1998. Biopsy results were compared after a 9-mo follow-up for both groups. There were 112 AGUS-EC cases from 82,754 conventional Pap smears (detection rate, 0.14%) compared with 58 cases from 82,252 TPPTs (detection rate, 0.07%) (P < 0.01). Biopsies were available in 72 of 112 patients from the conventional Pap smear group and 35 of 58 patients from the TPPT groups. Five dysplastic glandular lesions/ AIS were diagnosed by biopsy in the 35 patients (14.3%)from the TPPT group, compared with 2 of the 72 patients (2.8%) from the conventional Pap smear group (P < 0.05). There were no statistically significant differences between other follow-up diagnoses for the two methods. The use of TPPT resulted in fewer cases of AGUS-EC and better correlation with histology. The TPPT appears to be as sensitive as and more specific than the conventional Pap smear for detection of endocervical glandular lesions.

Advances in cervical screening technology

The Pap smear unquestionably is a successful screening test for cervical cancer. However, recent advances in technology have raised questions regarding whether the conventional Pap smear is still the standard of care. This article relates issues of screening and cost-effectiveness to the state of the art in thin layer preparations, cytology automation, human papillomavirus screening, human papillomavirus vaccines, and other cervical screening adjuncts. Perhaps nowhere in medicine is clinical decision making being more strongly influenced by market and other external forces than in cervical cytopathology.

Cell block preparation on residual ThinPrep sample

The liquid-based cytology system ThinPrep has overcome many of the deficiencies of the conventional Pap test. However, the cytologic appearances of the cells in the liquid-based medium are different and staffs of laboratories adopting the new system have to be specially trained. Even after the training sessions provided by the vendor, the cytology staff still face a sharp learning curve initially. One way to recognize the different appearances of cells in the liquid-based system is to look at paired split-sample cases from the same patient in laboratories offering the test as an adjunct to the conventional Pap test. Laboratories offering direct-to-vial testing may be able to overcome the difficulties with some cases by performing cell block sections of residual materials in the samples. The protocol for making cell blocks and its application in resolving difficulties with high-grade squamous and glandular epithelial lesions is illustrated in this report. Diagn. Cytopathol. 1999; 21:427-431.

ThinPrep vs. conventional smears in fine-needle aspirations of sarcomas: A morphological and immunocytochemical study

Very limited data exist describing the characteristics of sarcomas sampled by fine-needle aspiration (FNA) and processed by the ThinPrep (TP) method. We compared the cytopathological and immunocytochemical features of sarcoma aspirates prepared using both the conventional and TP method. We reviewed 70 sarcoma FNAs. Samples were first used to prepare conventional smears and the remainder of the specimen was rinsed in Cytolyt. The average number of slides examined per case was two for the TP method and five for the conventional technique. Immunocytochemistry for different markers was performed in a subset of cases. Sixty-five cases were positive for sarcoma both by conventional and TP methods. Five cases were positive by one method only. Cellularity was higher on conventional slides. In terms of cytoarchitecture, TP slides revealed fewer thick clusters, more single cells that were more evenly distributed, and sometimes distortion of expected cellular arrangements and architectural patterns. Cytomorphological and nuclear details were better preserved on TP slides. The background of TP slides revealed a reduction of blood but also some loss of necrosis and characteristic background tumor features. Immunocytochemical staining revealed superior results on TP slides. TP and conventional slides showed good correlation. TPs were excellent for immunocytochemistry and represent an alternative to conventional smears when expertise in slide preparation is not available. However, TPs may require additional experience in the interpretation of sarcomas, mainly related to the loss of tumor-specific background features. They are useful as an adjuvant to conventional smears in sarcoma diagnoses, particularly when special studies are needed. Diagn. Cytopathol. 1999;21:351-354.

Human papillomavirus infection in adolescents

The recent gain in knowledge of the genomic function of HPV has led to a greater understanding of the natural history of HPV infection in women, starting from infection to the development of invasive cancer. LSIL is reflective of a benign process associated with HPV replication, and in the majority of women, HPV is eradicated or put into some type of immunologic control so that it remains undetected. In contrast, in the minority of women who have persistent infection, HSIL and invasive cancer are more likely to occur. These findings can be translated clinically to suggest that LSIL can be followed up for a defined period of time and that HPV testing in older women may be useful to identify persistent HPV infections and subsequent risk for invasive cancers.

Use of the Thin Prep Pap Test in clinical practice

The Thin Prep Pap Test (Cytyc Corp., Boxborough, MA) received approval by the Food and Drug Administration in May 1996 as an alternative to the traditional conventional smear. The present direct-to-vial study assessed the utility of thin-layer technology for cervicovaginal screening in clinical practice. From May 1997-February 1998 (10 mo), 15,006 cervical smears were processed and evaluated; of these, 5,423 (36.1%) were conventional smears (CS) and 9,583 (63.9%) were Thin Prep slides (TP). Both methods were analyzed to compare specimen adequacy and detection rates of cervical lesions. The TP method reduced the "satisfactory but limited by" rate by 97% and the unsatisfactory rate by 63%. For low-grade squamous intraepithelial lesions (LSILs), TP slides yielded 3.6% (348/9,583) as compared to 0.98% (53/5,423) for CS, an increase of 267%. The TP method detected a threefold increase in the number of high-grade squamous intraepithelial lesions (HSILs) of 1.0% (100/9,583), as compared to 0.3% (17/5,425) for the CS group. The atypical squamous cells of undetermined significance/squamous intraepithelial lesion (ASCUS SIL) ratio was reduced by 54% in the TP group. In routine usage in our laboratory, the Thin Prep Pap Test yielded a significant increase in the detection of LSILs and HSILs as compared to conventional smears. Specimen adequacy was significantly improved.

Cervical screening adjuncts: recent advances

In an effort to reduce the false-negative rate of cervical cytologic findings, several new technologies have recently evolved. Automated cytologic testing (PapNet, AutoPap 300 QC) proposes to rescreen negative conventional cytologic findings to identify smears likely to be false negative. Fluid-based monolayers (ThinPrep, CytoRich) propose to reduce the false-negative rates by optimizing the collection and preparation of cells. Human papillomavirus deoxyribonucleic acid testing by Hybrid Capture has been proposed for a variety of screening and triage roles. Visual screening after application of acetic acid is done by cervicography by use of a photographic technique, whereas in speculoscopy the screening is done by direct visualization of the cervix by the primary care provider. Polarprobe uses biophysical parameters and a computer algorithm to give an instantaneous prediction of the likelihood of cervical disease. Each of these techniques, as well as the clinical experience with them, is reviewed. Current and possible future uses are discussed with regard to both clinical usefulness and cost-effectiveness.

Evaluation of the CytoRich technique for cervical smears

The aim of the study was to assess the ability of the CytoRich System to prepare optimal gynaecological smears for diagnosis. The diagnostic results obtained from evaluating 1,325 matched slide-pairs, prepared using conventional methods and thin-layer technology, were compared. Cytological material for study was obtained using the combined spatula-cytobrush sampling technique. An assessment of the pitfalls associated with the interpretation of these smears was also undertaken. Diagnostic agreement was achieved in 1,272 of the 1,325 matched slide-pairs (96.0%), and these included 1,172 negative, 50 atypical, 24 low-grade squamous intraepithelial lesion (LSIL), 24 high-grade SIL (HSIL), and two malignancies. A total of 1,309 cases showed the same diagnosis within one diagnostic grade for an agreement of 98.8%. Evaluation of the 53 discordant diagnoses revealed that the conventional smear identified a significantly greater number of abnormal smears than the CytoRich technique (P < .001). It is suspected that the use of the combined spatula-cytobrush sampling technique did not provide adequate residual specimen for CytoRich after conventional smear preparation. This limitation is evidenced by the fact that the CytoRich preparations showed a lower yield of endocervical cells (P < .001) and infectious organisms (P < .001) than was demonstrated on conventional smears. Despite a number of diagnostic pitfalls associated with the interpretation of thin-layer smears, these preparations were easier and faster to screen and showed well-preserved and evenly distributed cells. Thin-layer smears were also characterised by a marked reduction in thick cell groups, air drying artifact, and obscuring inflammation and blood. The results confirm the limitation of the combined spatula-cytobrush technique in these types of comparative studies.

Impact of training on cytotechnologists' interpretation of gynecologic thin-layer preparations

This study determines the impact of training on the accurate interpretation of gynecologic thin-layer (TL) preparations. A workshop was developed, implemented and evaluated. Training materials were developed with the assistance of a Delphi panel. Sixty-six self-selected cytotechnologists participated. The experimental group consisted of 40 participants tested before and after an educational intervention, using gynecologic TL preparations. The 26 individuals in the comparison group were given the same pre- and post-tests as the experimental group, but the educational intervention was not offered until after the tests were administered. Data were analyzed using the t-test for independent and dependent samples, McNemar's test, point biserial correlation, and descriptive statistics. No significant difference in test scores was observed between the two groups. A correlation was observed between prior exposure to TL preparations and cytotechnologists' test scores. No correlation between experience and test scores was found.

The AutoPap 300 QC System multicenter clinical trials for use in quality control rescreening of cervical smears: I. A prospective intended use study

BACKGROUND

The AutoPap 300 QC System is an automated device for the analysis of conventionally prepared cervical cytology slides. The AutoPap System selects an enriched population of cases for human quality control (QC) review. The device assigns a score based on the likelihood that a slide is abnormal. Cases are selected for QC rescreening that have scores exceeding a preset threshold corresponding to approximately the top 10% (or greater) of scores.

METHODS

AutoPap false-negative detection, compared with a 10% random QC process, was tested in a 6-center clinical evaluation study. At each site, a block of up to 150 consecutive negative slides (including detected false-negative cases) were selected randomly daily. All slides were run on the AutoPap System and rescreened by cytotechnologists for truth determination. The false-negative cases included in the top 10% group selected by AutoPap System then were compared with false-negative detection by the random selection process.

RESULTS

Fourteen thousand nine hundred fourteen cases were analyzed. The AutoPap-enriched 10% quality control group contained false-negative cases at rates 3 to 5 times that of the random selection method (P < 0.01). The sensitivity for all false-negative cases was 35% and was 52% for false-negative cases at the level of low grade squamous intraepithelial lesion and higher.

CONCLUSIONS

The AutoPap 300 QC System provides the potential for a marked increase in the number of false-negative cervical cytology cases that can be detected on QC rescreening. A significant reduction in laboratory false-negative rates can be expected if this device is utilized in routine practice.

Reproducibility study of cervical cytopathology in Mexico: a need for regulation and professional accreditation

Due to the high rate of false negative results in diagnosis of cervical cytopathology, in many countries its practice has been transformed through the application of several interventions aimed at medical regulation to improve diagnostic accuracy. Diagnostic reproducibility of gynecological cytopathology was evaluated in a series of 20 cytology specimens [Papanicolaou (Pap)] and 20 cervical biopsy. (CB) studies in different clinical stages, during 1994. The observation unit consisted of 30 pathologists who observed 2 groups of 20 Pap and 20 CB specimens. The standard was a cytopathologist certified by the Pathological Anatomy Council of Mexico. Intraclass reproducibility in gynecological cytopathology is low in Mexico. In a group analysis, concordance increased as clinical status of the cervical lesion increased. For moderate dysplasia, concordance in Pap was kappa = 0.04, compared to 0.23 in CB. Concordance of diagnosis of invasive cancer was 0.29 for Pap and 0.64 for CB. Using weighted kappa at the individual level for all possible diagnoses, concordance varied from 0.29 to 0.59 for Pap, and 0.42 to 0.65 for CB. The problem of reproducibility in cervical cytopathology in Mexico emphasizes the need for continuing education, uniform diagnostic criteria, and the advantages of a single operational classification-possibly the Bethesda System-since current classification systems are obsolete.

Comparison of ThinPrep and conventional preparations: nongynecologic cytology evaluation

ThinPrep processing, an automated cytopreparatory method, has been reported to show good correlation with conventional preparations and to reduce the rate of false-negative diagnoses. In a retrospective review of 230 consecutive nongynecologic cytology cases, we compare the ThinPrep (TP) method with conventional preparations (CP). There were 129 fine-needle aspiration (FNA) specimens from various sites, including 51 breasts, 40 thyroids, 14 lungs, 8 livers, and 16 miscellaneous sites. The sources of 101 body cavity fluids included 68 pleural/peritoneal effusions, 25 peritoneal/pelvic washings, and 8 miscellaneous sites. Each case was evaluated for cellularity, morphologic, details, and obscuring background material. Diagnoses of the TP slides were classified as insufficient, normal, benign, suspicious, or malignant. Each case was then correlated with the tissue diagnosis when available. In TP slides, cellular arrangements, nuclear details, and nuclear cytoplasmic ratio were preserved, while blood and diathesis were eliminated. There was no statistically significant difference between TP and CP in the diagnostic categories. However, in six cases of "insufficient for diagnosis" on FNA by CP, TP yielded sufficient cells and tissue fragments for diagnosis. One case each of FNA and body fluid with a diagnosis of "suspicious for malignancy" by CP was considered "positive" on TP slides. The overall sensitivity of TP was 97.6%, and the specificity was 92.9%. The positive predictive value was 93.0%. We conclude that the ThinPrep method shows good correlation with conventional preparations in both FNA and body fluids.

Use of fluorescent in situ hybridization to detect aneuploidy in cervical dysplasia

Fluorescent in situ hybridization (FISH) with alpha satellite DNA probes for chromosomes 11 and X were applied to normal, atypical, and dysplastic cervical-vaginal cytology smears to evaluate the detection of hyperploidy in suspected abnormal cells. Forty-six cases were obtained from fixed archival material. Eight cases with a morphological diagnosis of within normal limits (WNL) were directly selected to use as controls. The other 38 cases were blinded as study cases. These included five WNL, six ASCUS, six SIL-LG, 16 SIL-HG, four invasive squamous cell carcinomas, and one case of adenocarcinoma of the cervix. Cells with chromosome copy numbers suggesting hyperploidy (3-4 signals per chromosome specific probe) were found more often in higher grade dysplasia (Bethesda class SIL-HG) cases and less often in lower grade lesions (SIL-LG). All cases morphologically diagnosed as WNL were found to have normal copy number except for one control case which was hyperploid and, upon reexamination of the original slides, was upgraded from normal to atypical squamous cells of undetermined significance (ASCUS). Our FISH results are similar to those of previous studies involving flow cytometry and morphometric cytometry in which changes in ploidy correlated with progression toward higher grade lesions. However, FISH with enumeration probes offers a higher resolution view of the genome than is possible with flow cytometry or morphometry by allowing detection of specific chromosome changes in small numbers of affected cells in a routine cervical smear, and it may have the capacity to detect those cases in which progression toward high grade dysplasias is more likely.