Volume 17, Issue 2 pp. 73-81

Comparative study of the ThinPrep Pap test and conventional cytology results in a Canadian cohort

M. A. Duggan

M. A. Duggan

Departments of Pathology and Laboratory Medicine

Obstetrics and Gynecology, University of Calgary, Calgary, AB

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M. Khalil

M. Khalil

Departments of Pathology and Laboratory Medicine

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P. M. A. Brasher

P. M. A. Brasher

Division of Epidemiology, Prevention, and Screening, Alberta Cancer Board, Calgary, AB, Canada

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J. G. Nation

J. G. Nation

Obstetrics and Gynecology, University of Calgary, Calgary, AB

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First published: 21 March 2006
Citations: 13
M. A. Duggan, Department of Pathology and Laboratory Medicine, Room C1135, Foothills Hospital, 1403, 29th Street, NW, Calgary, T2N2 Y9 Alberta, Canada.
Tel.: (403) 944 4763; Fax: (403) 944 1460;
E-mail: [email protected]

Abstract

Objective: To compare the frequency of Pap test results in a prospective series of direct to vial ThinPrep tests to a cohort of conventionally prepared tests. To follow-up all test results for a minimum of 2 years and assess performance based on this outcome.

Methods: All women presenting for either routine screening or colposcopic examination in 2001 were enrolled in the ThinPrep cohort. A similar, population of conventionally prepared tests was extracted from the year 2000 laboratory data. Information on all concurrent and follow-up cervical specimens over the ensuing 2 years was retrieved.

Results: The ThinPrep cohort comprised 2288 Pap tests and the conventional, 2211. The frequency of normal [within normal limits (WNL) and benign cellular changes (BCC)] results in the ThinPrep cohort was 6% lower and the frequency of abnormal [≥atypical squamous cells of undetermined significance (ASCUS)] results was 6.8% higher. Respective ThinPrep and conventional cohort results were 1156 (51%) and 1291 (58%) WNL, 625 (27%) and 561 (25%) BCC, 101 (4%) and 65 (3%) ASCUS, 21 (1%) and 2 (0.1%) atypical glandular cells of undetermined significance, 301 (13%) and 224 (10%) low-grade squamous intraepithelial lesion (LSIL), and 74 (3%) and 40 (2%) high-grade SIL (HSIL) (P < 0.0001). Follow-up was available for nearly 80% of each cohort. LSIL or higher was confirmed in 57.5% (n = 266) of the abnormal ThinPrep and 60.9% (n = 190) of the abnormal conventional tests. The ThinPrep yield of confirmed tests however was almost 50% higher than the conventional test.

Conclusion: In this population, ThinPrep was superior to the conventional Pap test.

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