The manual screening of conventional pap smears for cervical cancer has been around for decades but liquid-based cytology (LBC) is now replacing it in many countries. Conventional smears are made by transferring material, taken from the cervix by a collection instrument, directly onto a glass slide. LBC slides are made by rinsing the collection instrument in liquid to produce a suspension, which is processed in a laboratory to produce a single layer of cells.
In the study published by Dr Davey, researchers used a computerised reading system, known as a Thin Prep Imager (TPI) to evaluate LBC slides. The programme would highlight any slides which needed further examination. These were looked at by a cytologist.
Samples were taken from 55,164 Australian women. From each single collection, a conventional cytology (CC) sample was made first, followed by a TPI sample. The most important finding of the study is that the ThinPrep Imager detected 1.3 more cases of high-grade cervical abnormalities per 1,000 women screened than the conventional cytology test.
Furthermore, fewer slides were found to be unsatisfactory using TPI – 1.78 percent compared to 3.09 percent with CC. Therefore, fewer women might be recalled for repeat smears than currently occurs if the ThinPrep Imager were introduced into population screening programmes.
The use of the TPI also increased detection of low-grade cell lesions and the researchers conclude this could result in higher rates of further testing. On the other hand, they say, together with the finding of improved detection of moderate and severe changes (CIN2 and CIN3), it does raise the possibility that the increased detection of abnormalities by TPI might allow longer intervals in between screening.
MEDICA.de; Source: British Medical Journal