Implications of gynaecological abnormalities in pre-selection criteria for cervical screening: preliminary evaluation of 3602 subjects in south India

Significance of DNA Replication Licensing Proteins (MCM2, MCM5 and CDC6), p16 and p63 as Markers of Premalignant Lesions of the Uterine Cervix: Its Usefulness to Predict Malignant Potential

Cervical cancer continues to be a leading cancer among women in many parts of the world. Nation-wide screening with the Pap smear has not been implemented in India due to the lack of adequately trained cytologists. Identification of biomarkers to predict malignant potential of the identified low risk lesions is essential to avoid excessive retesting and follow up. The current study analyzed the expression patterns of DNA replication licensing proteins, proliferation inhibitor protein p16INK4A and tumor suppresser protein p63 in cervical tissues and smears to assess the ability of these proteins to predict progression. Methods: Cervical smears and corresponding tissues were immunostained using mouse monoclonal antibodies against MCM2, MCM5, CDC6, p16 and p63. Smears were treated with a non-ionic surfactant sodium deoxycholate prior to immuno-cytochemistry. The standard ABC method of immunohistochemistry was performed using DAB as the chromogen. The immunostained samples were scored on a 0-3+ scale and staining patterns of smears were compared with those of tissue sections. Sensitivity and specificity for each of these markers were calculated taking histopathology as the gold standard. Result: All the markers were positive in malignant and dysplastic cells. MCM protein expression was found to be up-regulated in LSIL, HSIL and in malignancies to a greater extent than p16 as well as p63. CDC6 protein was preferentially expressed in high grade lesions and in invasive squamous cell carcinomas. A progressive increase in the expression of DNA replication licensing proteins in accordance with the grades of cervical intraepithelial lesion suggests these markers as significant to predict malignant potential of low grade lesions in cervical smears. Conclusion: MCMs and CDC6 can be applied as biomarkers to predict malignant potential of low grade lesions identified in screening programmes and retesting / follow up might be confined to those with high risk lesions alone so that overuse of resources can be safely avoided.

Evaluation of downstaging in the detection of cervical neoplasia in Kolkata, India

Unaided visual inspection or "downstaging" has been suggested as a potential alternative method for cervical cancer screening in developing countries. Our study was designed to evaluate the accuracy of downstaging to detect cervical neoplasia in a low-resource setting. A total of 6,399 women aged 30-64 years were screened with downstaging by trained nonmedical health workers. Two thresholds were used to define positive downstaging: "low threshold" when any visible abnormality on the cervix was considered positive and "high threshold" when selected abnormalities such as bleeding on touch, bleeding erosion, hypertrophied oedematous cervix, congested stippled cervix and growth or ulcer constituted the positive test. All women underwent a colposcopy examination. Biopsies were directed when colposcopy revealed abnormal lesions. True disease status was defined as histologically proven moderate dysplasia and worse lesions. Since all the participants received a diagnostic (reference) investigation (biopsy and/or colposcopy), sensitivity, specificity and predictive values were estimated directly. Low- and high-threshold downstaging were positive in 1,585 (24.8%) and 460 (7.2%) women, respectively. The sensitivities of low- and high-threshold downstaging to detect high-grade precursors and invasive cancers were 48.9% and 31.9%, respectively. The specificities were 75.8% and 93.3%, respectively. These results indicate that downstaging is not suitable as an independent primary screening modality for cervical neoplasia.

Evaluation of visual inspection as a screening test for cervical cancer

Visual inspection of the uterine cervix by paramedical personnel has been proposed for the early detection of cervical cancer, as an alternative to routine cytology screening in developing countries. We evaluated the performance of this procedure in detecting precursor lesions and cancer in a study involving 2843 married women in Kerala, India. Two thresholds were used to define a positive test. In the lower one, any abnormality was considered as positive. The cut-off point for the high threshold was one or more of the high-risk findings: bleeding on touch, suspicious growth/ulcer and hard, irregular, oedematous cervix. A Pap smear was performed on all subjects, and a biopsy was done for those with moderate dysplasia and above. A combination of cytology and histology findings was used as the 'gold standard'. Using the low threshold, 1279 (45%) women were positive on visual inspection, and with the higher threshold 179 (6.3%) were positive. There were six moderate dysplasias, nine severe dysplasias, ten carcinomas in situ and 13 invasive carcinomas. With the lower threshold, sensitivity and specificity to detect moderate dysplasia and above were 65.8% and 55.3% respectively; the values for severe dysplasia and above were 71.9% and 55.3% respectively and for invasive cancer were 92.3% and 55.2% respectively. With the higher threshold, the sensitivity decreased considerably (28.9% to detect moderate dysplasia lesions, 31.3% for severe dysplasia and 53.8% for clinical cancer) and the specificity increased to approximately 94%. At a lower threshold, the sensitivity was not satisfactory, and the test was highly non-specific; at a higher threshold sensitivity was even lower. Thus, the test characteristics of visual inspection are not very promising either as a preselection procedure for cytology or as a low-technology measure for cervical cancer screening in developing countries.

Early detection of cervical cancer by visual inspection: a population-based study in rural India

A total of 3784 women aged 35 and above living in 26 villages in rural Maharashtra state, India, were invited to undergo a pelvic examination, to evaluate the performance of unaided visual inspection by trained paramedical workers in detecting cervical cancer. Of this number, 2135 (56.4%) women complied with the invitation. Paramedical workers scored 1120 (57.3%) and 118 (6%) women as having abnormal cervices using the low- and high-threshold criteria respectively. There was good agreement between the visual findings of the paramedical workers and those of a gynaecologist. All subjects had a cervical smear. A total of 10 cervical cancers were detected by cytology/histology. The sensitivity of visual inspection by paramedical workers to detect cervical cancer was 90.0% using the low threshold and 60.0% with the high threshold to define a positive test. The values for specificity were 42.8% and 94.5% respectively. The results obtained by the gynaecologist were very similar. Cost savings implied by limiting cytology/other investigations to approximately half of the population pre-selected on the basis of visual inspection are likely to be offset by the necessity to repeat the test at frequent intervals, repeated follow-up visits and other investigations.