Trials That Matter: Liquid-Based Cervical Cytology: Disadvantages Seem to Outweigh Advantages
- George F. Sawaya, MD; and
- Harold C. Sox, MD, Editor
- From the University of California, San Francisco, San Francisco, CA 94143 (Dr. Sawaya).
Liquid-based cytology is a technique for preserving and preparing cells for cytologic study. As applied to cervical cytology, cells are obtained by scraping the external cervix uteri with a spatula and by rotating a cytobrush in the endocervix. Instead of being spread onto a glass slide and fixed, the samples are suspended in a vial of liquid preservative. In the laboratory, processing removes debris and places a thin layer of cells onto slides that are stained and read similarly to conventional cytology. Systematic reviews have concluded that the quality of the evidence about liquid-based cytology has not been good enough to judge its performance relative to conventional cytology (1, 2). The lack of large randomized studies comparing the 2 techniques is an important evidence gap (1, 3). In 2003, the U.S. Preventive Services Task Force (USPSTF) found the evidence insufficient to make a recommendation about using liquid-based cytology (4).
What Did This Landmark Trial Show?
Ronco and colleagues made a head-to-head comparison of conventional and liquid-based cytology (5). More than 45 000 women undergoing a new round of periodic cervical cancer screening were randomly assigned to conventional or liquid-based cytology in each of 9 sites. The same cytologists read both types of slides, and a supervisor or a panel of cytologists checked abnormal results. All centers participated in a program to monitor quality and to promote uniform interpretation among the centers.
The authors used …
This 100-word excerpt has been provided in the absence of an abstract.
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