Review slams liquid based cytology

Using liquid based cytology rather than conventional Pap tests may be a costly waste of time, a new review has concluded. A meta-analysis shows that the expensive new technology is neither more specific nor more sensitive than the conventional Pap smear. The new data shows that liquid-based cytology “does not lead to more disease detection and appears to increase false-positive testing,” according to an editorial that accompanies the report in Obstetrics and Gynaecology (2008;111:167-177). Dr Marc Arbyn and colleagues searched for papers where all patients were submitted to verification based on colposcopy and histology of colposcopy-based biopsies - and found there were very few high quality studies of liquid based cytology. They found that the sensitivity of liquid based cytology relative to conventional cytology “did not differ significantly.” They also showed that the specificity of liquid based cytology was lower when the presence of atypical squamous cells of undetermined significance was used as the cut-off. In an editorial, Dr George Sawaya wonders why the medical profession has jumped to adopt liquid-based cytology when so few high quality studies have been published. “How could a technology be so widely implemented before the appropriate studies have been performed to assess benefits and harms?” he asks. One reason may have been that clinicians were “enticed by claims of fewer unsatisfactory tests with liquid based cytology” despite the scanty evidence. In many cases, labs simply stopped offering conventional Pap smear tests, he suggests. “How the clinical laboratory has held such sway with clinical practice is enigmatic and disheartening, given current evidence.”...