Accuracy of conventional cytology: results from a multicentre screening study in India

Abstract

Objective:We conducted a multi-centre cross-sectional study in India to evaluate the accuracy of conventional cytology to detect high-grade squamous intraepithelial lesions (HSIL). Setting:Cross-sectional studies in Jaipur, Kolkata, Mumbai and Trivandrum, India, during 1999-2003. Methods: A common protocol and questionnaire were used to test 22,663 women aged 25-65 years with conventional cytology in ve cross-sectional studies. Three thresholds were used to de ne test positivity: atypical squamous cells of uncertain signi cance (ASCUS), low-grade squamous intraepithelial lesion (LSIL), or HSIL. All screened women were investigated with colposcopy, and biopsies were taken when necessary. The reference standard for nal disease status was histology or negative colposcopy. Data from the studies were pooled to evaluate the test characteristics for the detection of histologically con rmed HSIL. Results:The test positivity rates of cytology were 8.8% at ASCUS, 6.2% at LSIL and 1.8% at HSIL thresholds, and 355 women had histologically con rmed HSIL while 74 had invasive cancer. The pooled sensitivity, speci city, positive and negative predictive values at ASCUS threshold were 64.5%, 92.3%, 11.8% and 99.4% respectively. The corresponding values at LSIL threshold were 58.0%, 94.9%, 15.2% and 99.3%, while at the HSIL threshold they were 45.4%, 99.2%, 46.3% and 99.1%. The sensitivity varied between 37.8-81.3% at ASCUS , 28.9-76.9% at LSIL and 24.4-72.3% at HSIL thresholds. A signi cantly low sensitivity was observed in women aged 25-39 years (p<0.001). The wide variation in sensitivity across study sites persisted even after age standardisation. Conclusion:The sensitivity of cytology varied widely between the study sites. Findings from our study and other reviews indicate that sustained efforts in improving sampling, preparation and reading of cytological specimens and improvements in clinical judgement are essential to achieve concurrently high sensitivity and speci city. Cervical cytology screening programmes in developed countries of Western and Northern Europe, North America and Australia have been followed by a substantial reduction in disease burden. However, no signicant reduction in incidence and mortality from cervical cancer has been observed in developing countries where cytology screening programmes exist.2,3 The reasons for the lack of success include poor quality cytology and suboptimal coverage of target women with testing and treatment. Insuf cient sampling of cervical cells, imperfect preparation and staining of smears or failure to correctly identify cellular abnormalities in the smear lead to errors and a high frequency of false-negative reporting. The best estimates of the accuracy of conventional cytology screening based on the currently available data from cross-sectional studies, mostly conducted in developed countries, suggest that the range of sensitivity to detect cervical neoplasia is wide. There have been very few studies in developing countries addressing the test characteristics of cytology.W...

Re-evaluation of conventional cervical smears with particular reference to revised Bethesda system criteria: a 5 years blind retrospective and prospective study

“…These findings are in concordance with the study of Shorey et al, who reported 96.8% smears as satisfactory and 3.3% as unsatisfactory. [13] Similar results of around 3.8% unsatisfactory smears were also reported by Sankaranarayanan R et al [14] On comparing the cytological findings of the Conventional system and the Bethesda system, inflammation was found to be the most common finding in both the systems. Nonspecific inflammation was seen in similar number of cases by both the systems of reporting i.e 85.2% by the Conventional method and 86.5% by the Bethesda system.…”

Accuracy of concurrent visual and cytology screening in detecting cervical cancer precursors in rural India

“…Although our results indicate that the visual tests have similar sensitivity to that of cytology, albeit with significantly lower specificity and positive predictive value, for detecting histologically confirmed high-grade CIN and invasive cancer when concurrently evaluated in research settings as observed in cross-sectional studies in the past, 18,19 cytology had a higher sensitivity than the visual tests to detect high-grade CIN that were positive for p16 INK4a overexpression and/or high-risk HPV types. The specificity of VIA and VILI were low, compared to that of cytology.…”

Evidence-based Screening, Early Diagnosis and Treatment Strategy of Cervical Cancer for National Policy in Low-resource countries: Example of India

“…The screening process, along with the delays between screening, test results and ultimate treatment are major obstacles to the success of cytology-based programs in low-resource settings. Although cytology screening has been introduced in LMIC over the past 30 years, it has not resulted in the expected decreases in cervical cancer incidence and mortality similar to those observed in the HIC, primarily because of the above mentioned hurdles associated with low coverage of the target population (Dzuba et al, 2005 the CIN2 and CIN 3 (53% in HIC, and 26-65% in LMIC) (Almonte et al, 2007;Cuzick et al, 2006;Sankaranarayanan et al, 2004b;Sarian et al, 2005), repeated screening at regular intervals is necessary for the programmes to be effective. This low sensitivity in developed countries is overcome by organized periodic screening, which is not feasible with the opportunistic screening carried in low-resource setting.…”