66 Test performance of dual stain cytology in a cervical screening population with high prevalence of HIV and precursor lesions

Abstract

<h3>Introduction/Background</h3> Cervical cytology and human papillomavirus (HPV) tests are effective as cervical cancer screening tools but have limitations. Higher expression of p16 and Ki-67 biomarkers have been associated with more severe cervical lesions. Dual stain cytology (DSC) has therefore been proposed in triaging screen-positive patients to improve overall specificity and diagnostic accuracy. <h3>Methodology</h3> During a cross-sectional cervical cancer screening study, women with any positive screening result were tested with p16/Ki-67 DSC. Worst grade histology was regarded as final diagnosis. Here we describe screening test results as well as test performances for detecting significant cervical intraepithelial neoplasia (CIN2+). Histology results was available for 92.1% (399/433) women: CIN2+ 55.1% (220/399), CIN3+ 28.3% (113/399), invasive cancer 3.0% (12/399). Verification bias adjustment (VBA) was applied to account for missing histology data. <h3>Results</h3> Included were 433 women who were screen-positive, mean age 40 years, range 25–64 years; 57.0% (247/433) were HIV positive. Overall test positivity for cytology (threshold atypical squamous cells of undetermined significance [ASCUS]) was 50.6% (219/433) and for HPV 73.2% (317/433), of which 33.1% (105/317) was HPV16/18-positive. DSC was positive in 65.4% (283/433) women. Overall DSC positivity was unexpectedly high in this study population and increased with higher grade histology: 50.0% (89/178) in ≤CIN1, 76.6% (82/107) in CIN2, 87.0% (87/100) in CIN3 and 83.3% (10/12) in cancer cases. Two cancer cases were missed by DSC but were positive on both HPV and cytology. Estimated sensitivity/specificity/PPV/NPV for predicting CIN3+ was, for cytology (ASCUS+) 75.4%/57.5%/39.9%/86.2%; for HPV 67.8%/41.0%/30.1%/77.3%; for DSC 84.8%/41.0%/35.0%/87.8% respectively. <h3>Conclusion</h3> Our results confirm the correlation of DSC with lesions of increased severity. In this unique screening population, DSC improved on the sensitivity of both HPV DNA and cytology but failed to improve the specificity of either of these tests. <h3>Disclosures</h3> No conflict of interest to declare.