Comparison of liquid-based cytology with conventional cytology for detection of cervical cancer precursors: a randomized controlled trial.
BACKGROUND
Liquid-based cytology has been developed as an alternative for conventional cervical cytology. Despite numerous studies and systematic reviews, controversy remains about its diagnostic accuracy.


OBJECTIVE
To assess the performance of liquid-based cytology compared with conventional cytology in terms of detection of histologically confirmed cervical intraepithelial neoplasia (CIN).


METHODS
Cluster randomized controlled trial involving 89,784 women aged 30 to 60 years participating in the Dutch cervical screening program at 246 family practices. One hundred twenty-two practices were assigned to use liquid-based cytology and screened 49,222 patients and 124 practices were assigned to use the conventional Papanicolaou (Pap) test and screened 40,562 patients between April 2004 and July 1, 2006. Patients were followed up for 18 months through January 31, 2008.


METHODS
Screening for CIN using liquid-based cytology or conventional papanicolaou (Pap) test and the blinded review of all follow-up of screen-positive women (blinded to the type of cytology and the initial result).


METHODS
Intention-to-treat and per-protocol analysis of the detection rates of and positive predictive values for histologically verified CIN in both cytology systems. Outcomes are presented as crude and adjusted rate ratios (adjustment for age, urbanization, study site, and period).


RESULTS
The adjusted detection rate ratios for CIN grade 1+ was 1.01 (95% confidence interval [CI], 0.85-1.19); for CIN grade 2+, 1.00 (95% CI, 0.84-1.20); for CIN grade 3+, 1.05 (95% CI, 0.86-1.29); and for carcinoma, 1.69 (95% CI, 0.96-2.99). The adjusted positive predictive value (PPV) ratios, considered at several cytological cutoffs and for various outcomes of CIN did not differ significantly from unity.


CONCLUSIONS
This study indicates that liquid-based cytology does not perform better than conventional Pap tests in terms of relative sensitivity and PPV for detection of cervical cancer precursors.


BACKGROUND
trialregister.nl Identifier: NTR1032.
Siebers
Albertus G
AG
Department of Pathology, Radboud University Nijmegen Medical Centre, 824, PO Box 9101, 6500 HB Nijmegen, The Netherlands. b.siebers@pathol.umcn.nl
Klinkhamer
Paul J J M
PJ
Grefte
Johanna M M
JM
Massuger
Leon F A G
LF
Vedder
Judith E M
JE
Beijers-Broos
Angelique
A
Bulten
Johan
J
Arbyn
Marc
M
D000328:Adult; D005260:Female; D006801:Humans; D008875:Middle Aged; D065006:Papanicolaou Test; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis*; D014626:Vaginal Smears / Q000295:instrumentation / Q000379:methods; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis*