NEW YORK (Reuters Health) – Compared to conventional cytology, liquid-based cytology is more than twice as sensitive in detecting cervical intraepithelial neoplasia (CIN) grade 2 or higher, without a decrease in positive predictive value, according to a German study.

“Addition of computer assistance to liquid-based cytology did not further improve sensitivity,” Dr. Stefanie J. Klug, at the Technical University of Dresden, and colleagues report.

As they note in their paper in the International Journal of Cancer online November 23, liquid-based cytology has replaced conventional cytology for cervical cancer screening in some countries, but its superiority is unclear.

The current study reports the findings of a trial conducted in Germany in which 20,672 women were screened for cervical cancer at 20 gynecology practices that were randomly assigned to use conventional cytology or liquid-based cytology, with or without computer-assisted imaging. Patients with positive results were invited to undergo colposcopy.

Using a cutoff of CIN2+, the detection rate was 0.37% with conventional cytology, 1.04% with manually assessed liquid-based cytology, and 1.21% with computer-assisted liquid-based cytology, the authors found.

This translates to a relative sensitivity of manual liquid-based cytology (LBC) versus conventional cytology of 2.74, and of 3.17 with computer-assisted LBC versus conventional cytology, the team reports.

On the other hand, positive predictive values of the three techniques were 38%, 48% and 44% for conventional cytology, manual LBC and computer-assisted LBC, respectively, indicating no deterioration with liquid-based cytology despite its higher sensitivity, according to the report.

While concluding that LBC was significantly more sensitive for the detection of CIN than conventional cytology, Dr. Klug and colleagues note that there is no organized system for cervical cancer screening in Germany and little centralized quality control. Since the quality of conventional cytology may be higher in organized programs, they conclude, “The results of our study may be transferred to countries without high quality organized cervical cancer screening.”

SOURCE: A Randomized Trial Comparing Conventional Cytology to Liquid-Based Cytology and Computer Assistance