PubMed · 7748639
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A M Arnot. 1994. Cervical screening.. https://pubmed.ncbi.nlm.nih.gov/7748639/
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Minor cytologic abnormalities of the cervix, such as atypical squamous cells of undetermined significance (ASCUS), are vastly more common than high-grade squamous intraepithelial lesions or invasive cancer. Current guidelines for the management of ASCUS include repeating the Papanicolaou (Pap) smear at specific intervals, referring all patients for colposcopy or using an adjunctive test such as hybrid capture human papillomavirus (HPV) testing or cervicography. The usefulness of the Pap smear is limited by its considerable false-negative rate and its dependence on clinician and laboratory performance. Colposcopy is a highly sensitive procedure, but many patients with ASCUS have normal colposcopic findings. The hybrid capture test not only measures quantitative HPV load but also detects both oncogenic and nononcogenic HPV types, thereby increasing the probability that serious cervical disease is not missed. Hybrid capture sampling is simple to perform, and positive results are strongly associated with cervical dysplasia. HPV testing in women with ASCUS can be used as an adjunctive test to identify those with HPV-associated disease; it can also serve as a quality assurance measure. Together, repeat Pap smears and HPV testing should identify most patients with underlying cervical dysplasia. Combined testing may also minimize the number of unnecessary colposcopic examinations in women who have no disease.
BACKGROUND: In a study using a split-sample design, liquid-based cytology (ThinPrep Processor, Cytyc Corporation, Boxborough, MA) was compared with the conventional Papanicolaou (Pap) smear in Guanacaste, Costa Rica. The study provides the first population-based comparison of the ThinPrep screening technology and includes "gold standard" measures of diagnostic accuracy. METHODS: The population-based study was performed among over 8000 women residing in a Costa Rican province with a high incidence of cervical carcinoma. Conventional smears were prepared and diagnosed in Costa Rica, while the residual material on the sampling device was collected into a liquid preservative and shipped to the U.S., where ThinPrep cytologic slides were prepared and diagnosed. Cytologic diagnoses based on the two techniques, categorized according to the Bethesda System, were compared with a "gold standard" final case diagnosis for each patient, also based on Bethesda terminology, that reflected an integrated interpretation of all available data, including cytology, histology, and cervicography. Results were also compared with the results of HPV DNA detection (Hybrid Capture, Digene Corporation, Silver Spring, MD). RESULTS: ASCUS was the threshold for colposcopy referral. There were significantly more women referred according to this threshold with the ThinPrep slide (12.7%) than with the conventional smear (6.7%, P<0.001). Compared with the final case diagnosis, referral by ThinPrep slides detected 92.9% of cases with high grade squamous intraepithelial lesions (HSIL) and 100% of carcinoma cases. Smears detected 77.8% of HSIL and 90.9% of carcinomas. Thus, ThinPrep cytology was significantly more sensitive in the detection of HSIL and cancer (McNemar test, P<0.001). Adjudication of cases in which the ThinPrep and smear diagnoses disagreed, using the final case diagnoses and the HPV DNA test results as reference standards, suggested that the ThinPrep method was detecting additional true SIL as opposed to false-positives. CONCLUSIONS: In a population-based study of high risk women, ThinPrep cytology demonstrated significantly increased sensitivity for detecting HSIL and carcinoma, with a concurrent significant increase in colposcopy referrals.