Automated, liquid-based cytology was found to be no more sensitive or specific than standard Pap smears in detecting cervical intraepithelial neoplasia or cancer, according to a report.
In what they described as “the largest high-quality study performed in a population-based setting with blind verification of follow-up outcomes of all test-positive cases,” the study's investigators found that liquid-based cytology was not superior to Pap testing.
Until now, neither screening method has been definitively established as better than the other, because there haven't been enough well-designed comparative studies, wrote Dr. Albertus G. Siebers of Radboud University Nijmegen (the Netherlands) Medical Center and associates.
Nevertheless, liquid-based cytology has virtually replaced conventional Pap smears in the United States. It is preferred by most laboratories, because specimens are more easily and rapidly scanned under the microscope, Dr. Mark Schiffman and Dr. Diane Solomon wrote in an editorial (JAMA 2009;302:1809-10).
The investigators assessed testing outcomes in 84,322 Dutch women aged 30-60 years who were screened at 246 family practices. A total of 45,818 women attended practices that had been randomly assigned to use liquid-based cytology and 38,504 attended practices that had been assigned to use Pap smears.
In an intention-to-treat analysis, the adjusted detection rate ratios for cervical intraepithelial neoplasia (CIN) grade 1+ was 1.01; for CIN grade 2+ was 1.00; for CIN grade 3+ was 1.05, and for carcinoma was 1.69.
“Our study found no difference in sensitivity in terms of histological detection rates of cervical lesions, or in the positive predictive values between liquid-based cytology and Pap test, indicating that the accuracy of both methods is comparable,” the investigators reported (JAMA 2009;302:1757-64).
Mr. Siebers reported no conflicts of interest. Dr. Schiffman and Dr. Solomon reported that they are serving as medical monitors of the Costa Rican HPV Vaccine Trial, which is supported in part by GSK Biologicals and GlaxoSmithKline.