Comparative study: conventional cervical and ThinPrep Pap tests in a routine clinical setting.

The conventional Papanicolaou smear is associated with variable false positive and false negative rates, difficulties with interpretation and high unsatisfactory and suboptimal rates. Newer fluid-based methods such as the ThinPrep 2000 system (Cytyc Corp., Boxborough, MA) are said to overcome these difficulties. The aim of this study was to compare the conventional smear with the ThinPrep method in a busy, routine cytology screening laboratory setting. One thousand split samples were evaluated. Using ThinPrep, the results showed an increased sensitivity and a dramatic improvement in specimen adequacy, with a combined 17.2% reduction in 'unsatisfactory' and 'suboptimal' reports. Screening time per slide was also reduced to 3-4 min. In conclusion, we report an increase in sensitivity, a reduction in screening time and a dramatic improvement in specimen adequacy with the ThinPrep method.     

Accuracy of liquid-based Pap tests: comparison of concurrent liquid-based tests and cervical biopsies on 782 women with previously abnormal Pap smears

OBJECTIVE: To evaluate the diagnostic performance of a liquid-based Pap test, the ThinPrep Pap test (TP) (Cytyc Corp., Boxborough, Massachusetts, U.S.A.), by comparing concurrent TP and cervical biopsy results on 782 patients who were referred for colposcopy because of previously abnormal conventional Pap smears (CPs). STUDY DESIGN: The ability of TP diagnoses of atypical cells of undetermined significance (ASC-US) and squamous intraepithelial lesions (SILs) to predict biopsy diagnoses of cervical intraepithelial neoplasia (CIN) was analyzed using chi2 and McNemar tests. RESULTS: The rate of agreement between diagnoses of SIL by TP and CIN by biopsy was 74.7%. ASC-US accounted for 16.0% of TP diagnoses. ASC-US had biopsy diagnoses of CIN 1 in 60% and CIN 2/3 in 12.8% of cases. For TP diagnosis of low grade SIL, biopsy diagnoses of CIN 2/3 were found in 13.5% of cases. For TP diagnoses of ASC-US and higher, the proportions of TP and cervical biopsies in comparable diagnostic categories were statistically significant (p < 0.001), with TP having sensitivity of 89.4% and positive predictive value of 89.7% for the detection of CIN. The false positive rate for TP was 8.1%, but rescreening confirmed the presence of abnormal cells in 51 of 63 (81.0%) cases of ASC-US or higher having negative biopsies. TP had a false negative rate of 8.3% and negative predictive value of 61.3%. Rescreening showed that most (77.6%) of the false negative TP specimens failed to have abnormal cells on the slides. CONCLUSION: For patients having previously detected cervical abnormalities by CP, concurrent TP demonstrated the following: (1) that it has high diagnostic accuracy for SIL, (2) that ASC-US was diagnostically equivalent to LSIL, and (3) that false negative TP for SIL can be attributed primarily to sampling rather than cytotechnologists' screening errors.     

Significance of atypia in conventional Papanicolaou smears and liquid-based cytology: a follow-up study

The diagnosis of atypical squamous epithelial cells, borderline nuclear changes, is associated with some controversy, as it encompasses benign, reactive, as well as possible neoplastic conditions. The aim of this study was to evaluate the follow-up diagnoses of cytological atypia in conventional Papanicolaou smears (CP) and liquid-based samples by the ThinPrep Pap Test (TP). A total of 1607 CP smears from 1 January 2000 to 31 December 2000 and 798 TP samples from 1 January 2002 to 31 December 2002 diagnosed as atypia were included. The results show that the detection rate of atypia in cervical cytological samples was reduced by 41.3% (P < 0.001) in TP compared with CP. Cytological and histological follow-up data showed the presence of neoplastic lesions in 34.7% of patients screened by TP versus 22.3% of patients screened by CP, corresponding to a 55.6% increase in TP (P < 0.001). Follow-up diagnosis of mild dysplasia was seen more than twice as often in TP than in CP (12.8% versus 5.0%, P < 0.001). The prevalence of moderate and severe dysplasia was significantly increased with 26.7% in TP compared with CP (21.9% versus 17.2%, P < 0.01). In conclusion, the ThinPrep Pap Test yielded a significant decrease in atypia rates compared with the conventional Papanicolaou test. In subsequent follow-up the percentage of neoplastic lesions was significantly increased in the ThinPrep Pap Test samples.     

Comparative study of the ThinPrep Pap test and conventional cytology results in a Canadian cohort

OBJECTIVE: To compare the frequency of Pap test results in a prospective series of direct to vial ThinPrep tests to a cohort of conventionally prepared tests. To follow-up all test results for a minimum of 2 years and assess performance based on this outcome. METHODS: All women presenting for either routine screening or colposcopic examination in 2001 were enrolled in the ThinPrep cohort. A similar, population of conventionally prepared tests was extracted from the year 2000 laboratory data. Information on all concurrent and follow-up cervical specimens over the ensuing 2 years was retrieved. RESULTS: The ThinPrep cohort comprised 2288 Pap tests and the conventional, 2211. The frequency of normal [within normal limits (WNL) and benign cellular changes (BCC)] results in the ThinPrep cohort was 6% lower and the frequency of abnormal [> or =atypical squamous cells of undetermined significance (ASCUS)] results was 6.8% higher. Respective ThinPrep and conventional cohort results were 1156 (51%) and 1291 (58%) WNL, 625 (27%) and 561 (25%) BCC, 101 (4%) and 65 (3%) ASCUS, 21 (1%) and 2 (0.1%) atypical glandular cells of undetermined significance, 301 (13%) and 224 (10%) low-grade squamous intraepithelial lesion (LSIL), and 74 (3%) and 40 (2%) high-grade SIL (HSIL) (P < 0.0001). Follow-up was available for nearly 80% of each cohort. LSIL or higher was confirmed in 57.5% (n = 266) of the abnormal ThinPrep and 60.9% (n = 190) of the abnormal conventional tests. The ThinPrep yield of confirmed tests however was almost 50% higher than the conventional test. CONCLUSION: In this population, ThinPrep was superior to the conventional Pap test.     

The effect of tamoxifen on cervical squamous maturation in Papanicolaou stained cervical smears of post-menopausal women

Using cervical smears obtained as part of routine gynaecological examinations, a retrospective study of the effects of the drug tamoxifen on squamous epithelial maturation of the cervix of post-menopausal women being treated for advanced breast cancer was made. The degree of squamous epithelial maturation was quantitated by using the Maturation Index and the Maturation Value. Although tamoxifen is a synthetic, non-steroidal compound classified as anti-oestrogenic, the findings indicate that this drug commonly produces a level of squamous maturation indicative of oestrogenic stimulation in Papanicolaou stained cervical smears from post-menopausal patients receiving this drug. Knowledge of the oestrogenic effect of tamoxifen in the cervix can obviate clinical concern about endometrial carcinoma.     

Efficacy of Ki-67 antigen staining in Papanicolaou (Pap) smears in post-menopausal women with atypia—an audit

In cervical smears from post-menopausal women with mucosal atrophy it can be difficult to distinguish atrophic epithelial cell groups from neoplastic cell groups on cytomorphological criteria only. The consequence of post-menopausal atypia is that the woman is referred for a repeat smear after local oestrogen treatment or for colposcopy. We investigated whether immunocytochemical expression of Ki-67 (MIB-1) on the primary Papanicolaou-stained smear could be of any diagnostic help. Our data showed that negative Ki-67 expression is a very reliable indicator of a normal atrophic cell pattern, and by using this method on the original smear we were able to reduce the false-positive cytologic diagnoses by 86%.     

Relationship between the diagnosis of epithelial abnormalities and the composition of cervical smears

The significance of endocervical columnar cells as a high-quality parameter of cervical smears was studied. In a cohort of women with two successive screenings, the consistency of the cellular composition of the cervical smears and the relation between the cellular composition of the smears and the frequency of the diagnosis of abnormal epithelial changes was investigated. At the first screening, a significantly higher number of epithelial abnormalities was found in smears with endocervical columnar cells than in smears without endocervical columnar cells. A significantly higher number of abnormal epithelial changes was found on the second screening in smears from women whose smears from the first screening did not contain endocervical columnar cells than in smears from women whose smears from the first screening did contain endocervical columnar cells. The presence of endocervical cells should be considered a very important indicator of the quality of cervical smears. The chance of missing an abnormal epithelial change is increased in smears without endocervical columnar cells. When endocervical columnar cells are absent, the smear should be considered to be of unreliable quality and a repeat smear should be taken after a short interval, unless the absence of columnar cells can be satisfactorily explained.     

Intraobserver and interobserver variability in the diagnosis of epithelial abnormalities in cervical smears

In a study of variability in the diagnosis of epithelial abnormalities, cervical smears with abnormalities of different severity were rescreened twice by 19 observers with an interval of six months. The observers focused on grading atypicality of squamous, squamous metaplastic and endocervical columnar epithelial cells; their results were compared (1) for the two screenings to assess intraobserver variability and (2) to "review" (final) diagnoses to assess interobserver variability. When the same observer rescreened a smear, 83.3% of the diagnoses did not differ more than one grade between two screenings; however, average intraobserver variability differed considerably for individual observers. The intraobserver variability was only slightly (not significantly) influenced by the years of experience in cytopathology of the observers. Intraobserver variability proved to be an important factor in incorrect diagnoses: 49.1% of the smears with false-negative and 52.9% with false-positive diagnoses at the first rescreening were correctly assessed at the second rescreening. Of all diagnoses made at rescreening, 80.9% were in agreement with the review diagnosis. The interobserver variability also showed considerable differences between observers; however, there was a strong influence of the experience of the observer on the interobserver variability. Atypicality grading of endocervical columnar epithelium by the observers showed a low correlation with the review diagnoses. The relatively low accuracy in the evaluation of this kind of epithelial abnormality is likely to be attributable to the low incidence of abnormal changes of endocervical columnar epithelium. The results of this study point to intraobserver variability as the main cause of false diagnoses. When wrongly diagnosed, severe epithelial abnormalities are more often underestimated than completely overlooked. Apart from training in cytopathology, the establishment of laboratory protocols for multiple screening of even minor abnormalities seem to be the most effective means of reducing the number of false diagnoses.     

False-negative Papanicolaou smears from women with cancerous and precancerous lesions of the uterine cervix

The occurrence from 1980 to 1989 of false-negative Papanicolaou smears in women with cancerous and precancerous lesions of the uterine cervix was studied. The 4,781 cases of cancer (2,814 invasive carcinomas and 593 carcinomas in situ) and precancerous lesions (418 severe dysplasias, 748 moderate dysplasias and 208 mild dysplasias) included 70 cases (1.5%) with false-negative smears. These 70 cases included 43 invasive carcinomas (61.4%), 17 carcinomas in situ and adenocarcinomas in situ (24.2%), and 10 dysplasias (14.4%); all were diagnosed histologically. The mean age of women with false-negative smears was 44.1 +/- 13.7 years. Review of the original cytologic samples showed a screening error in 41 cases (58.5%), an interpretation error in 2 cases (2.9%) and a sampling error in 27 cases (38.6%). Methods for eliminating false-negative smears are discussed.     

Classification of cervical smears with discordance between the cytologic and/or histologic ratings

The problems of diagnostic variability between certified cytotechnologists was studied. Three cytology laboratories submitted a total of 28 cervical smears that had a discordance between the cytologic and/or histologic ratings. Eight independent cytotechnologists provided blind readings on each slide, expressed as "absence of cervical intraepithelial neoplasia (CIN)" to "CIN III." The median rating was absence of CIN or CIN I for 8 slides, CIN II for 5 and CIN III for 15. With a kappa value greater than 0 reflecting agreement beyond chance expectation and a value of 0.40 indicating fair agreement, the kappa value for 8 X 28 ratings was 0.36 (P = .0001), with a 90% confidence interval (CI) between 0.34 and 0.37. The kappa value was 0.14 (P = .10), with a 90% CI between 0.10 and 0.18, on a subsample of nine smears with two or more positive cytology diagnoses but a negative histology. Sixteen of the 28 slides represented cases of histologically proven cancer. Treating cytologic diagnoses of CIN II and CIN III as positive, the sensitivity of the cytologist with reference to histology varied between 71% and 86% while the specificity ranged from 18% to 62%. The positive predictive value was 1/2.5 to 1/1 and the negative predictive value was 1/6 to 1/1. The predictive power (true positives/false positives) ranged from 1.0 to 2.2. The cytodiagnosis of these cervical smears from cases of discordance thus exhibited limited reliability. Standardization of the relevant cytologic knowledge and its routine application is needed to improve the level of performance.     

Reduced alcohol use in the staining of Pap smears: a satisfactory low-cost protocol for cervical cancer screening

OBJECTIVE: To describe a low-cost Papanicolaou staining procedure that can be applied to conventional and monolayer gynecologic preparations. STUDY DESIGN: The amount of alcohol consumed in the procedure, which normally accounts for > 80% of the cost of processing, was reduced drastically by (1) using only 1 modified cytoplasmic counterstain (EA type), thereby (2) reducing the number of alcohol rinses by over half Orange-G dye is omitted. RESULTS: The resultant effect of the modified staining protocol is quite satisfactory and attractive to screening eyes: nuclear details are sharp and crisp, while the cytoplasm contains transparent differential staining with blue-green and pink. CONCLUSION: A reduction in the cost of staining should encourage cervical cancer screening, especially in developing countries, where cost is a limiting factor, thus making it possible for more women to be screened without increasing the cost of the program.     

Endocervical glandular cell abnormalities in conventional cervical smears: evaluation of the performance of cytomorphological criteria and HPV testing in predicting neoplasia

Objective:  To analyse the correlation between cytomorphological criteria in smears with atypical glandular cells (AGC) or adenocarcinoma in situ (AIS) and human papillomavirus (HPV) reflex test results with different neoplastic histological diagnoses, particularly to distinguish between glandular and squamous neoplasia.
Methods:  A series of 155 women with glandular abnormalities in their conventional cervical smears was included: 106 with AGC, 35 with AGC associated with high-grade squamous intraepithelial lesion (HSIL) and 14 with AIS. Two reviewers evaluated 35 cytomorphological criteria and hybrid capture II (HCII) was performed in all cases. Colposcopy was carried out in all cases and biopsy in 126/155. For statistical purposes, predictive values and odds ratio (OR) were calculated, followed by chi-square automatic interaction detection.
Results:  Histology detected 56 cases of squamous and 17 of glandular intraepithelial or invasive neoplasia. Predictive values of the papillary groups and feathering criteria for glandular neoplasia were, respectively, 80.0% and 73.3%. Feathering was the criterion with the highest OR for distinguishing glandular from squamous neoplasia and also for distinguishing between glandular and non-neoplastic diagnosis. Rosettes and pseudostratified strips did not perform as well. Multivariant Classification and Regression Trees analysis identified feathering as the best criterion for distinguishing between glandular, squamous and non-neoplastic diagnoses regardless of HPV status.
Conclusions:  Feathering was the best criterion for predicting glandular neoplasia.     

Follow-up study of atypical glandular cells in gynecologic cytology using conventional Pap smears and liquid-based preparations: impact of the Bethesda System 2001

OBJECTIVE: This study evaluated the impact of the Bethesda System (TBS) 2001 in reporting of atypical glandular cells (AGC) when using conventional Pap smears (CS) and liquid-based cytology preparations (LBC). STUDY DESIGN: Follow-up information for all atypical glandular cells of undetermined significance (AGUS)/ AGC cases encountered in Queen Mary Hospital from July 2000 to June 2004 was analyzed. The difference in percentages associated with certain end points when using different reporting systems and preparation methods were compared. The age trends and time interval between cytologic diagnosis and detection of positive end points were studied. RESULTS: More than half of these cases turned out to be "negative." The majority with "negative" end points belonged to the "not otherwise specified" (NOS) groups (including atypical endometrial cells) in TBS 2001. The connotation of "favor neoplastic" carried a high positive predictive value for significant lesions. Most of the significant outcomes were discovered within the subsequent 6 months. A decreased reporting of "AGC, NOS" and an increased reporting of "atypical endocervical cells, NOS" were noted when using LBC. CONCLUSION: Subcategorization of AGC in TBS 2001 according to cellular origin and risk of malignancy, which is further enhanced by application of LBC, is useful.