Liquid-based cytology and conventional cervical smears

BACKGROUND: This study compared the findings of cervical cytology screening by ThinPrep Papanicolaou (Pap) tests (TP) with the findings of screening by conventional cervical smears (CS) in a screening population involving what to the authors' knowledge is the largest sample of ThinPrep Pap tests published to date. METHOD: Data from 191,581 CS that were screened in the period from March 1, 1998 to February 28, 2000 were compared with data from 190,667 TP performed from March 1, 2000 to February 28, 2002 and that were obtained from the same sources. RESULTS: With TP, the unsatisfactory rate was reduced from 0.48% to 0.32%. Fewer cases were considered to be suboptimal (19.12% vs. 12.97%). The detection rates of squamous cell carcinomas, adenocarcinomas, and high-grade squamous intraepithelial lesions (HSIL) were essentially unchanged in the TP group (0.005%, 0.003%, and 0.25%, respectively) compared with the rates for the CS group (0.01%, 0.006%, and 0.25%, respectively). There was an increase in the detection of atypical squamous cells of undetermined significance (ASCUS; 3.74% vs. 3.19%) and low-grade SIL (LSIL; 1.67% vs. 1.01%) with a decrease in the ASCUS-to-LSIL ratio from 3.15 for CS to 2.33 for TP. The detection of atypical glandular cells of undetermined significance (AGUS) increased slightly from 0.07% to 0.09%. The proportion of cells reported to have reactive atypia dropped from 2.71% to 1.48%. Limited biopsy correlation (range, 73.2-76.2%) confirmed the increased sensitivity of TP. More actinomyces (1.07% vs. 0.52%) were detected in TP samples despite of a similar portion of intrauterine-device users. The average primary screening and rapid rescreening time of each slide were reduced from 8 minutes to 4 minutes and from 2 minutes to less than 1 minute, respectively. CONCLUSIONS: The preliminary experience of the authors of the current study appears to support the use of the ThinPrep Pap test to enhance the efficiency of cervical cytology screening.