NEW YORK (Reuters Health) – Liquid-based cytology is no better than conventional Pap tests in detecting cervical cancer precursors, according to a report in the Journal of the American Medical Association for October 28.

Liquid-based cytology was developed as an alternative to conventional cervical cytology, in the hopes of reducing the false-negative and false-positive test results seen with the older method, Albertus G. Siebers, from Radboud University Nijmegen Medical Center, The Netherlands, and colleagues note. In addition, because of how it is performed, liquid-based cytology allows reflex human papillomavirus testing and other molecular tests to be done as well.

Whether liquid-based cytology actually provides more accurate results than conventional cytology, however, is unclear, due largely to a lack of well-designed comparative studies, the report indicates.

The current randomized trial featured 89,784 women, 30 to 60 years of age, who were participating in a Dutch cervical screening program at 246 family practices. From April 2004 to July 1, 2006, half of the practices were assigned to use liquid-based cytology and half continued to use conventional cytology.

The subjects were followed through January 2008. The main outcome measure was the sensitivity and positive predictive values for histologically verified cervical intraepithelial neoplasia (CIN) with each method.

Liquid-based cytology was comparable to conventional cytology in detecting all cervical cancer precursors (CIN grade 1+, 2+, and 3+). Only when overt carcinoma was present did liquid-based cytology show an advantage (adjusted rate ratio, 1.69).

Similarly, no significant differences in positive predictive values were noted between the two types of cytology, the report indicates.

“The importance of the trial by Siebers et al might be greatest in countries with centrally managed screening programs that are debating cytology methods,” Dr. Mark Schiffman and Dr. Diane Solomon, from the National Cancer Institute, Bethesda, Maryland, comment in a related editorial.

They add, “The choice comes down to cost-effectiveness issues related to laboratory productivity, slide adequacy, and ease of ancillary molecular testing, but not accuracy.”

Reference:
JAMA 2009;302:1757-1764,1809-1810.