title: Direct comparison of liquid-based and conventional cytology in a South African screening trial.
abstract: Our study directly compares the performance of liquid-based (LBC) and conventional cytology for detecting high-grade cervical intraepithelial neoplasia and cancer (CIN 2+) in high-risk, previously unscreened women. As part of a larger randomized clinical trial assessing the efficacy and safety of a "screen and treat" program for cervical cancer prevention, 5,652 South African women, aged 35 to 65 years, were screened using either ThinPrep or conventional Papanicolaou cytology. The cytology method used (i.e., ThinPrep or conventional) was rotated on a 6-month basis for the duration of the study. Directly following collection of the cytology specimen, all women underwent colposcopy with endocervical curettage and biopsy of all colposcopic abnormalities. Assessment of cytology and histology results was blinded and results were compared using histology-confirmed CIN as the "gold standard." The accuracy of LBC and conventional cytology was statistically equivalent, although the sensitivity of conventional cytology was at least 5 percentage points higher at all cutoff levels. For example, at a cytology cutoff level of low-grade squamous intraepithelial lesion, the sensitivity of LBC was 60.3% for CIN2+ vs. 69.1% for conventional cytology and specificity was 94.1% and 94.5%, respectively. LBC specimens were significantly less likely to be "satisfactory-but-limited-by" (6.5% vs. 27.9%) but significantly more likely to be unsatisfactory (2.2% vs. 0.8%). Thus, in this high-risk population, the sensitivity of LBC is no greater than the sensitivity of conventional cytology. Because of the higher unit cost of LBC, low resource settings should carefully consider the potential benefits and drawbacks of LBC before adopting this new technology.
authors.affiliation: Department of Pathology, Columbia University, New York, NY 10032, USA.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Taylor
authors.forename: Louise
authors.initials: L
authors.lastname: Kuhn
authors.forename: William
authors.initials: W
authors.lastname: Dupree
authors.forename: Lynette
authors.initials: L
authors.lastname: Denny
authors.forename: Michelle
authors.initials: M
authors.lastname: De Souza
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Wright
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D003127:Colposcopy; D003584:Cytological Techniques / Q000191:economics / Q000379:methods; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data; D006801:Humans; D008403:Mass Screening / Q000592:standards / Q000706:statistics & numerical data; D008867:Microtomy; D008875:Middle Aged; D065006:Papanicolaou Test; D012016:Reference Values; D012680:Sensitivity and Specificity; D013019:South Africa; D013048:Specimen Handling; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis*; D014626:Vaginal Smears; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis*