The validation of cervical cytology. Sensitivity, specificity and predictive values

Statistics and methods for the validation of the results of cytologic screening for cervical cancer and its precursors were examined. Many of the methods commonly used, including the calculation of sensitivity and specificity on raw data, contain flaws that undermine their conclusions. Using a large computerized database of 748,871 cytologic screenings of 277,842 women over a ten-year period, the value of screening was examined. Only subsequent histologic examinations within one year were accepted to validate positive initial cytologic diagnoses; only two subsequent cytologic screenings within the next three years were accepted to validate negative initial cytologic diagnoses that had not been followed by a histologic examination. Cases not meeting these criteria were excluded from the initial analysis. From these data, the predictive value of a negative cytologic examination was determined to be 99.8%; the predictive value of a positive cytologic examination was 73.4% for an initial diagnosis of mild-to-moderate dysplasia, 90.6% for a diagnosis of severe dysplasia/carcinoma in situ, 94.5% for a diagnosis of carcinoma in situ or microinvasive carcinoma and 95.5% for an initial diagnosis of invasive carcinoma. Cases with an initial "questionable" cytologic diagnosis had a positive predictive value of only 64.0%. Extrapolation from the validated cases to the entire screened population showed an overall sensitivity of 80% and a specificity of 99.4% for cytologic screening for cervical cancer. The sensitivity was slightly lower for mild and moderate dysplasia (78.1%) and slightly higher for carcinoma in situ and severe dysplasia (81.4%) and invasive carcinoma (82.3%).     

Quality control measures for cervical cytology laboratories

The results of three quality control measures for evaluating a cytopathology laboratory's performance in the diagnosis of cervical abnormalities are presented. The sensitivities of cervical cytology were estimated to be 95.5% or 93.1% (using two different methods of analysis) for the detection of histologically diagnosed invasive squamous cell carcinoma of the cervix and 60% for the detection of adenocarcinoma and adenosquamous carcinoma of the cervix in 1983. The positive predictive values for a histologic diagnosis of neoplasia after cytologic reports of CIN III and invasive carcinoma were 92.5% and 99%, respectively. Repeatability of a negative cytologic result exceeded 98%. These results indicate that accurate cervical cytologic reporting can be achieved. Regular monitoring of the type described, which is both practical and reasonably comprehensive, is recommended for all laboratories.     

False-negative results in cervical cytologic studies

The appropriate interval between cervical cytologic screening studies is a matter of considerable controversy, with a major consideration being the problem of false-negative results. To determine the rate of false-negative cervical cytologic results in our laboratory and to determine how these failures occur, tissue-proven cases of carcinoma in situ, invasive squamous-cell carcinoma, endocervical adenocarcinoma and lymphoid malignancy involving the cervix with negative Papanicolaou smears obtained within one year prior to the tissue diagnosis were reviewed. Over the four-year period from 1980 through 1983, 339 patients had tissue-proven cervical malignancies. Of these, 66 had false-negative Papanicolaou smears, representing a 20% overall false-negative rate. These false-negative smears were rescreened. For all types of cervical malignancy, the majority of errors were due to sampling. No malignancy was missed disproportionately by either cytotechnologists or cytopathologists. We plan to utilize these data for quality control purposes and for continued review of future performance.     

Rapid cervicovaginal smear screening: method of quality control and assessing individual cytotechnologist performance

AIM: To validate the method of rapid screening (RS) in the detection of cervical lesions and false-negative results as well as in quality control of cytotechnologist performance. MATERIAL AND METHODS: The RS method was validated on Papanicolaou-stained and initially conventionally analysed vaginal, cervical and endocervical (VCE) smears collected in an opportunistic programme for the detection of cervical carcinoma. The study included 3680 VCE smears from the Department of Gynaecologic Cytology, University Department of Gynaecology and Obstetrics, Zagreb University Hospital Center, Zagreb and from the Department of Clinical Cytology, Osijek University Hospital, Osijek. Histologically verified abnormal findings accounted for 10% of the study samples. Thirteen cytotechnologists, with no previous experience in RS, performed the test. Each slide was examined using the 'step' technique for 1.5 minutes, the findings were classified as negative or abnormal, and the abnormal ones were also classified according to differential cytological diagnosis. The results were compared with those obtained on initial screening. Abnormal findings from a group of initially negative findings were reanalysed using conventional methods to make definitive cytological diagnosis. RESULTS: RS yielded a sensitivity of 83.7%, specificity of 93.7%, positive predictive value of 62.4%, negative predictive value of 97.9% and diagnostic accuracy of 92.6%. Relative to the initial abnormal differential cytological diagnosis, the diagnostic value of RS increased with lesion severity [54.8%, 68.0% and 91.3% for cervical intraepithelial neoplasia (CIN) I, CIN II and CIN III respectively]. RS detected 38 additional positive findings; 94.2% of these were atypical squamous cells of undetermined significance (ASCUS)/abnormal glandular cells undetermined significance (AGUS) and CIN I. The rate of additional positive findings was 1.14% (38/3135). The false-negative rate of initial screening was 9.4% (38/406), and individual cytotechnologist sensitivity was 60.0-100.0%. CONCLUSION: RS could be introduced as an efficient method of quality control to improve the sensitivity of cytological screening as well as for quality control of cytotechnologist performance.     

薄层液基细胞学检测及HPV检测对宫颈癌筛查价值的系统评价

目的：系统评价薄层液基细胞学检查（TCT）及人类乳头状病毒（HPV）检查在子宫颈癌筛查中的应用价值。方法：检索收集2000年以来,Cochrane数据库、Pubmed、MEDLINE、Webofscience、EMBASE、万方数据库、清华同方数据库、维普数据库中与TCT及HPv检测在宫颈癌筛查（癌前病变及早期宫颈癌）诊断方面的相关文献,参照Cochrane系统评价的方法对资料进行统计分析。结果：共有12篇文献纳入研究,TCT合并的敏感性0．65（95％CI,0．62-0．68）,特异性0．93（95％CI,0．92-4）．93）,阳性预测值8．25（95％CI,5．65-12．04）,阴性预测值0．27（95％CI,0．18-0．41）,合并SROC曲线下面积AUC=0．889,Q值0．819。HPV合并敏感性0．69（95％CI,O．67~0．71）,特异性O．91（95％CI,0．90-0．91）,阳性预测值3．93（95％CI,2．99-5．18）,阴性预测值0．17（95％CI,0．09～0_31）,合并SROC曲线下面积AUC=0．871,Q值0．801。结论：薄层液基细胞学检查在宫颈癌筛查中具有较高的诊断准确度,与HPV联合检测可提高诊断的准确性。     

Inflammatory atypia and the false-negative smear in cervical intraepithelial neoplasia

The effectiveness of cervical cytologic screening is compromised by the increasingly recognized prevalence of false-negative smears. Our previous studies suggested that some false-negative cytologies can be accounted for by smears showing cervical intraepithelial neoplasia (CIN) reported as inflammatory atypia; we found that at least 4% of 5,752 consecutive smears had been underreported in this manner. In the present study, that data was reanalyzed to derive 95% confidence limits for the number of CIN smears reported as inflammatory atypia. Using several differing estimates of cytologic screening sensitivity, it is speculated that, under certain testable assumptions, colposcopy of patients with cytologic diagnoses of inflammatory atypia may be one cost-effective approach to finding CIN cases missed by screening. If confirmed, these findings imply that laboratory quality assurance efforts, traditionally directed to the most serious cytologic diagnoses, should also focus in part on nondysplastic atypia.     

Ki67与MRI在宫颈癌根治性手术后宫颈癌淋巴结转移中评价对比

摘要 目的：探究Ki67与MR在宫颈癌根治术后宫颈癌淋巴结转移中评估价值的对比。方法：选择2016年1月至2018年1月于我院接受宫颈癌根治术的151例宫颈癌患者,分别对其实施Ki67检测及MRI检测,以病理学检测结果为金标准,计算两种检测方式对宫颈癌淋巴结转移评估的准确度、敏感度、特异度、阳性预测值及阴性预测值,并进行对比分析。结果：检测评估发现,MRI对宫颈癌淋巴结转移评估准确度为31.79 %,灵敏度为46.75 %,特异度为16.22 %,阳性预测值为36.73 %,阴性预测值为22.64 %。Ki67检测对宫颈癌淋巴结转移评估准确度为42.38 %,灵敏度为52.56 %,特异度为31.51 %,阳性预测值为45.05 %,阴性预测值为38.33 %。两种检测方式对比显示Ki67对宫颈癌淋巴结转移具有更高的诊断准确度。结论：3 相比于MRI检测,Ki67对宫颈癌淋巴结转移具有更高的诊断准确度、特异度和阴性预测值,分析其原因与MRI检测受个体因素影响更大有关。     

Laboratory performance measures: evidence against low-risk women explaining low detection rates of high-grade abnormalities

OBJECTIVE: When a laboratory has a low reporting rate of high-grade abnormality for its cervical cytology specimens, the question arises whether this is due to the laboratory screening a low-risk group of women. This study was undertaken to explore the hypothesis that a low-risk group of women were screened by Victorian laboratories not meeting the recommended minimum standard for the detection of high-grade abnormalities. METHODS: A cohort of 28 094 women was established comprising women whose cervical cytology was reported in 2000 by laboratories not meeting the recommended standard of 0.5% high-grade abnormalities in their reporting of community smears. Outcome measures included the prevalence of high-grade abnormality on the next cytology test for the women, the positive predictive value of the cytology reports of high-grade abnormality, and the standardized incidence ratio for a later diagnosis of cervical cancer. RESULTS: The prevalence of high-grade abnormality was 0.36% on the index cytology compared with 0.68% on the first subsequent cytology report. Sixty-nine per cent (60/87) of the index cytology reports of high-grade abnormality were confirmed as high-grade abnormalities on histology, compared with 70.8% (121/171) for the first subsequent reports of high-grade abnormality. During 70 015 person-years at risk, nine cases of cervical cancer were observed compared with 5.21 expected cases, giving a standardized incidence ratio of 1.73 (95% CI 0.79-3.28). CONCLUSIONS: These results do not support a hypothesis that the low detection rate for high-grade abnormalities is due to the women comprising a low-risk group for cervical neoplasia.     

HPV16感染检测和TCT筛查联用的临床应用

目的评估人乳头瘤病毒(Human papillomavirus,HPV)16感染和液基薄层细胞学(thinprep cytologic test,TCT)筛查在预测宫颈病变中的临床价值。方法以门诊537例高危型HPV感染疑似宫颈病变女性为对象,进行HPV16感染分析、液基薄层细胞学和阴道镜病理检查,以病理活检为金标准,比较HPV16感染筛查方法、TCT筛查方法以及二者联用在筛查中的敏感度、特异度等指标,判断其临床应用价值。结果 HPV16感染筛查方法的敏感度为62.9%,特异度为83.5%,阳性预测值为53.4%,阴性预测值为88.2%;TCT筛查方法的敏感度为41.2%,特异度为92.7%,阳性预测值为62.9%,阴性预测值为84.0%;二者联合筛查,以HPV16感染或TCT异常为阳性,敏感度为84.7%,特异度为75.8%,阳性预测值为51.2%,阴性预测值为94.3%。结论 HPV16感染联合TCT异常筛查可以提高筛查的灵敏度,特异度也在可接受范围内,可以作为宫颈防癌初筛方法。     

Organisation of cervical cytology screening in Croatia: past, present and future

This presentation highlights strengths and weaknesses of cervical cytology screening in Croatia, with particular reference to the opportunistic screening, the use of conventional Papanicolaou (Pap) test and the analysis of some organizational, educational and performance issues that are associated with it. Its aim is to propose measures to improve the efficacy of cervical cytology screening in order to reduce cervical cancer mortality. Currently, in excess of 450,000 Pap tests/ year are examined at 35 laboratories scattered throughout the country. All of these laboratories use standard operating procedures including internal and external quality control. They employ a total of 68 cytologists and 91 cytotechnologists. The sensitivity of cervical screening in Croatia is 90.0%, specificity 98.6%, positive predictive value 92.3%, negative predictive value 98.1% and overall diagnostic accuracy 97.2%. The high diagnostic accuracy of cervical cytology is attributed to the long-standing tradition of education and training of cytologists (postgraduate MSc course since 1967, independent residency since 1974) and cytotechnologists (since 1968). This tradition spanning more than half a century means that today in Croatia there is a developed network of cytology laboratories staffed by highly competent cytologists and trained cytotechnologists. The high accuracy of cancer detection through Pap tests provides strong evidence in support of cervical cytology screening remaining the basic method of prevention for cervical carcinoma. However, some modifications to the current situation are needed. These relate primarily to opportunistic screening. The current screening coverage rate is 68%, although there is capacity, which would allow for all women at risk, i.e. those aged 25-64, to be screened once in three years. The screening coverage relates mainly to those women visiting gynecological out patient clinics for unrelated conditions. A properly organized and controlled national screening programme should replace this. This should be accompanied by the introduction of alternative, highly sensitive methods of sample collection and preparation, such as are available through the introduction of new technologies, e.g. liquid based cytology.     

Comparing disease screening tests when true disease status is ascertained only for screen positives

Disease screening is a fundamental part of health care. To evaluate the accuracy of a new screening modality, ideally the results of the screening test are compared with those of a definitive diagnostic test in a set of study subjects. However, definitive diagnostic tests are often invasive and cannot be applied to subjects whose screening tests are negative for disease. For example, in cancer screening, the assessment of true disease status requires a biopsy sample, which for ethical reasons can only be obtained if a subject's screening test indicates presence of cancer. Although the absolute accuracy of screening tests cannot be evaluated in such circumstances, it is possible to compare the accuracies of screening tests. Specifically, using relative true positive rate (the ratio of the true positive rate of one test to another) and relative false positive rate (the ratio of the false positive rates of two tests) as measures of relative accuracy, we show that inference about relative accuracy can be made from such studies. Analogies with case-control studies can be drawn where inference about absolute risk cannot be made, but inference about relative risk can. In this paper, we develop a marginal regression analysis framework for making inference about relative accuracy when only screen positives are followed for true disease. In this context factors influencing the relative accuracies of tests can be evaluated. It is important to determine such factors in order to understand circumstances in which one test is preferable to another. The methods are applied to two cancer screening studies, one concerning the effect of race on screening for prostate cancer and the other concerning the effect of tumour grade on the detection of cervical cancer with cytology versus cervicography screening.     

FRD特殊染色技术在宫颈疾病筛查中的结果分析

目的:研究FRD特殊染色技术(FRD)在宫颈疾病筛查中的结果情况,为临床诊疗提供依据。方法:选取2015年5月到2016年5月我院就诊宫颈疾病筛查者306例,对所有患者进行FRD和液基细胞学检测,两种检测有一项提示阳性则行阴道镜病理检测,以病理检测为标准,比较两种检测方法诊断价值。结果:宫颈癌前病变和宫颈癌筛查中两种检测方法敏感度分别为87.6%、84.0%,特异性分别为69.0%、63.3%,诊断符合率分别为79.7%、75.8%,阳性预测值分别为79.2%和78.4%,阴性预测值分别为81.7%和71.4%,Kappa值为0.56和0.48,比较差异无统计学意义(P0.05)。结论:FRD与液基细胞学检测筛查宫颈癌前病变和宫颈癌效果相似,但是FRD操作简便,值得在临床上应用。     

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.     

Correlation of endoscopic cytology and histology in oesophageal cancer: results in Porto Alegre,RS—Brazil

A retrospective study of oesophageal cytopathology at the Hospital de Clínicas de Porto Alegre (HCPA), RS, Brazil, from 1989 to 1992 was made to assess the sensitivity, specificity, predictive values and accuracy of endoscopic cytology and biopsy; and study the correlation between cytopathological and histopathological diagnosis. Specimens from 94 patients were available for review. The final diagnosis was based on surgical pathology and follow up. The 81 patients with cancer of the oesophagus had the following sex distribution: 64 males and 17 females (a 3.7–1 ratio). No tumour was found in 13 patients. The following conclusions were made: (i) there is excellent correlation between cytology and histology in oesophageal lesions sampled by endoscopy; (ii) a correct positive cytologic report was obtained in 77 (95%) of the 81 proven oesophageal cancers; a false-negative or unsatisfactory result was given in four patients. A false-positive diagnosis of cancer was not made. There were 13 true-negative reports. These findings result in a sensitivity of 95% with 95% confidence intervals (CI) of 90.26–99.74%; a specificity of 100% (CI of 98.5–100%); a positive predictive value of 100% (CI of 99.3–100%); a negative predictive value of 76% (CI of 55.7–96.3%); (iii) a correct positive histological report was obtained in 67 (83%) of the 81 proven oesophageal cancers; a false-negative or unsatisfactory result was given in 14 patients. A false-positive diagnosis of cancer was not made. There were 13 true-negative reports. These findings result in a sensitivity of 83% with 95% CI of 74.82–91.18%; a specificity of 100% (CI of 98.5–100%); a positive predictive value of 100% (CI of 99.25–100%); a negative predictive value of 48% (CI of 29.16–64.84%); (iv) of 81 patients with proven cancer, in 79 (98%) at least one of the methods was positive. In only two patients with cancer were both methods negative. These findings result in a combined sensitivity of 98% (CI of 94.92–100%); a specificity of 100% (CI of 98.5–100%); a positive predictive value of 100% (CI of 99.31–100%); and a negative predictive value of 87% (CI of 70–100%). Our series confirms the value of the combined use of cytology and biopsy for the investigation of oesophageal lesions. However, it should be remembered that even with the combined use of cytology and biopsy there are some tumours that will be negative by both procedures: we had only two such cases, confirming the rarity of such an event.     

Obligations to provide appropriate patient management

The Pap test is a successful method of preventing cervical cancer, but it does have significant false negative and false positive rates. The main aim of screening is the detection of precursor lesions, both regression and progression of which may occur, making it difficult to decide upon follow-up and further therapy. Around the world there are many differences, as a far as the frequency of the disease, the organization and economic background of the health care system, the use of different additional diagnostic tools and even the terminology considered. All these factors underline the importance of a consensus on a "minimum level" of obligations to provide appropriate patient management. The screening interval should be two to five years, in some cases even annually. The cytopathologist has an obligation to recommend repeat smears in cases of cytologic abnormalities likely to regress. We recommend the use of standard terminology and stress the importance of a "common language" in cervical cytology. Colposcopy and biopsy are obligatory in cases of HSIL and cancer. We suggest that in severe cases women should be provided with detailed written and verbal information.     

Intraobserver and interobserver variability in the quality assessment of cervical smears

Intraobserver and interobserver variability in assessing the quality of cervical smears, as measured by the presence or absence of endocervical columnar cells and squamous metaplastic cells, was evaluated. In total, 180 cervical smears representing the most important cytologic diagnoses were anonymously rescreened twice by 19 observers with an interval of six months. An absence of endocervical columnar cells was proven to correlate with a high percentage of false-negative diagnoses. Intraobserver agreement on the presence or absence of endocervical columnar cells was 85.7% between the two screenings. A predictive value of 57.7% was found for a negative scoring (absence of these cells) while the predictive value of a positive scoring (presence of endocervical cells) was 87.3%. Of the observer scorings, 83.9% concurred with the final diagnosis; there was no significant correlation between that concurrence and the number of years of experience in cytopathology of the observer. For squamous and squamous metaplastic cells in the cervical smear the predictive value of a negative scoring (absence) was only 20.6%. Compared to the final diagnosis, 69.5% of these scorings matched. A significant and relatively high correlation with the experience of the observer was found for the scoring for the presence of metaplastic cells. Even though the predictive values of these quality scorings were relatively low a significantly higher risk for false diagnoses was established when negative scorings were given. It is therefore advisable to have smears with negative scorings for endocervical columnar cells and squamous metaplastic cells always rescreened by another observer.     

Cervicovaginal cytology in uterine adenocarcinoma and adenosquamous carcinoma. Comparison of cytologic and histologic findings

To investigate the diagnostic accuracy and to characterize the findings in false-negative cases, the results of cervicovaginal cytology in 56 adenocarcinomas and 25 adenosquamous carcinomas (42 cervical, 36 endometrial, 2 metastatic and 1 arising synchronously from both cervix and endometrium) were reviewed, including review of the actual slides in 56 cases. Overall, 80% of the initial cytologic diagnoses resulted in diagnostic curettage (i.e., cytology was effectively positive); 84% of the postreview diagnosis were effectively positive. Nine cytology slides showed no malignant cells; eight of these negative smears showed repair, five were atrophic, two showed a high estrogen effect and one had enlarged atypical bare nuclei. These false-negative diagnoses were associated with an endometrial primary site (P less than .01), endometrioid histology (P less than .005), low-grade or intermediate-grade histology (P less than .005), small size of tumor (P less than .05) and absence of cervical involvement (P less than .005) in those cases in which a hysterectomy was performed. False-negative diagnoses were not associated with an absence of endocervical cells or with scanty cellularity. Of 39 cervical and 28 endometrial carcinomas with a positive cytologic diagnosis (initially or after review of the available slides), cytology correctly identified the primary site in 18% and 54% of the cases, respectively. Cytology incorrectly classified the anatomic site of four cervical and three endometrial carcinomas and considered one case arising in both the endometrium and cervix to be endometrial. Routine cervicovaginal cytology does have a role in screening for uterine glandular carcinoma; to maximize its diagnostic sensitivity, we suggest using a recommendation for curettage in the report of positive cases so that all of the varied cytologic diagnoses associated with glandular carcinomas will receive a uniform clinical response. In those cases with preserved cancer cells, a correlation can be made with the histologic type of the carcinoma, rather than with the anatomic site.     

Clinical evaluation of the EA-rosette test in the early detection of cervical cancer

It was previously found that a negative EA-rosette test, showing EA-rosette-forming cells in a cervical cell suspension, excluded the presence of cells of invasive carcinoma (predictive value of 99.9%). This study on 2,462 patients confirmed the applicability of the EA-rosette test in screening for precancerous as well as cancerous lesions. In 98.6% of the cases of dysplasia, carcinoma in situ and invasive carcinoma, the cervical cell suspensions contained EA-rosette forming cells (the rosette test was positive). With a negative EA-rosette test, the probability of missing a specimen with class III cytology (mild/moderate dysplasia) was 1.4%, of missing one with class IV cytology (severe dysplasia/carcinoma in situ) was 0.8% and of missing one with class V cytology (invasive carcinoma) was 0.25%. The predictive value of a negative EA-rosette test was 98.6%. The false-negative rate for negative EA-rosette tests was 3.7% for invasive carcinoma, 17.5% for carcinoma in situ and severe dysplasia and 41.4% for mild to moderate dysplasia.     

Comparative accuracy of anal and cervical cytology in screening for moderate to severe dysplasia by magnification guided punch biopsy: a meta-analysis

Background

The accuracy of screening for anal cancer precursors relative to screening for cervical cancer precursors has not been systematically examined. The aim of the current meta-analysis was to compare the relative accuracy of anal cytology to cervical cytology in discriminating between histopathologic high grade and lesser grades of dysplasia when the reference standard biopsy is obtained using colposcope magnification.

Methods and Findings

The outcome metric of discrimination was the receiver operating characteristic (ROC) curve area. Random effects meta-analysis of eligible studies was performed with examination of sources of heterogeneity that included QUADAS criteria and selected covariates, in meta-regression models. Thirty three cervical and eleven anal screening studies were found to be eligible. The primary meta-analytic comparison suggested that anal cytologic screening is somewhat less discriminating than cervical cytologic screening (ROC area [95% confidence interval (C.I.)]: 0.834 [0.809–0.859] vs. 0.700 [0.664–0.735] for cervical and anal screening, respectively). This finding was robust when examined in meta-regression models of covariates differentially distributed by screening setting (anal, cervical).

Conclusions

Anal cytologic screening is somewhat less discriminating than cervical cytologic screening. Heterogeneity of estimates within each screening setting suggests that other factors influence estimates of screening accuracy. Among these are sampling and interpretation errors involving both cytology and biopsy as well as operator skill and experience.     

National registry of cervical cytologic diagnoses in The Netherlands

The national cervical cytology registry being developed in the Netherlands is described. A large-scale screening program for cervical cancer has been in effect since 1975 in the region of the cities of Nijmegen, Utrecht and Rotterdam. At the start of the pilot projects, laboratories agreed upon a uniform protocol for reporting cytologic findings and recommendations for follow-up examinations in cases of abnormalities. Based on the results of the three pilot projects, in 1985 the Dutch government decided to organize a nationwide screening program for cervical cancer. All pathology laboratories involved in this national screening program are using the same screening protocol and the same coding system for cytologic and histologic diagnoses. By the end of 1989, all pathology laboratories will be linked to a central pathology diagnosis data base (PALGA). Linkage of screening results to previous and follow-up cytologic and histologic findings will enable epidemiologic studies on a regional or national level. Each physician who has submitted specimens will, next to the cytology reports, periodically receive reviews of the number of smears submitted, the cellular composition (quality) of those smears and the follow-up findings. The execution of requests for follow-up examination will be supervised by the participating pathology laboratories. The national cervical cytology registry will enable registration of all relevant cytologic and histologic diagnoses in a uniform way, but will also establish a unique high-quality national data bank, which will be of great value in the analysis of the effectiveness of the national screening program for cervical cancer. It will enable measurement of the impact of various screening protocols and give insight into the behavior of cervical cancer and the progressive or regressive character of its early stages. It will also offer the opportunity to initiate and evaluate quality control protocols.