Is Liquid-Based Cervical Cytology Better Than Conventional?

No improvement was found in detecting grade 2 or 3 cervical intraepithelial neoplasia.

Although liquid-based cervical cytology has become a standard technique for cervical cancer screening, evidence that it is better than conventional cytology is meager. To compare the two methods, Italian investigators randomized more than 45,000 women (age range, 25–60) presenting for Pap smears to undergo screening using either conventional or liquid-based cytology.

In an intention-to-screen analysis, the proportion of women who had at least one technically unsatisfactory or uninterpretable cytology result was significantly lower in the liquid-based cytology group; this reduction was greater in women aged 25 to 34 than in older women. No significant increase in sensitivity for grade 2 or higher cervical intraepithelial neoplasia was found, and the positive predictive value was significantly lower for liquid-based cytology regardless of the cutoff point used to refer women for colposcopy and biopsy to document cervical dysplasia. Liquid-based cytology was significantly more sensitive in detecting grade 1 or higher cervical intraepithelial neoplasia.

Comment: Although liquid-based cytology was more sensitive than conventional cytology in detecting mild cervical abnormalities, it was not better at detecting serious lesions. Yet, most insurers in the U.S. pay for the more expensive liquid-based cytology. It is more important to obtain Pap smears than to be concerned about the method used to prepare them.

— Robert W. Rebar, MD

Published in Journal Watch General Medicine June 12, 2007

Citation(s):
Ronco G et al. Accuracy of liquid based versus conventional cytology: Overall results of new technologies for cervical cancer screening randomised controlled trial. BMJ 2007 May 21; [e-pub ahead of print]. (http://dx.doi.org/10.1136/bmj.39196.740995.BE)