A thin-layer, liquid-based pap test for mass screening in an area of China with a high incidence of cervical carcinoma. A cross-sectional, comparative study.

OBJECTIVE To confirm the accuracy of the ThinPrep Pap Test (Cytyc Corp., Boxborough, Massachusetts, U.S.A.) on the basis of histologic diagnosis by biopsy and the detection of human papillomavirus (HPV) DNA in mass screening. STUDY DESIGN A total of 1,997 women residing in Xiangyuan County, Shanxi Province, P.R.C., an area with a high incidence of cervical carcinoma, were enrolled in this study. We collected exfoliative cervical samples from all subjects into a liquid buffer (Preserv-Cyt [Cytyc]) and utilized for both cytologic screening using the ThinPrep Pap Test and HPV DNA testing. Subsequent colposcopic biopsies were taken on all subjects. All the tests were performed in an independent and blinded fashion. We compared the ThinPrep Pap test with colposcopic biopsy and HPV test. RESULTS High grade squamous intraepithelial lesions (HSIL) (CIN 2/3) were identified in 74 (3.7%) of 1,993 women adequately assessed, and there were 12 cases of squamous cell carcinoma (SCC). The false negative rate of ThinPrep cytology was 3.2% for biopsy-confirmed CIN 3 and 9.3% for CIN 2. Twenty-seven (87%) of the 31 women with biopsy-confirmed CIN 3 and 12 (100%) of 12 with biopsy-confirmed SCC had a diagnosis of either HSIL or greater abnormalities on ThinPrep cytology. In addition, the HPV DNA detection rates offered a good correlation between cytology and biopsy. CONCLUSION The ThinPrep Pap performed extremely well in this primary screening trial. We found a good correlation between ThinPrep cytology and colposcopic biopsy on detection of HSIL and SCC; cervical specimens collected in ThinPrep liquid buffer serve as a direct test for HPV as well.