According to a report in the Journal of the American Medical Association in October, 2009 a study of nearly 90,000 women in the Netherlands concluded that the liquid-based cytology. a commonly used alternative to conventional Pap tests, was not superior to the Pap test in detecting cervical cancer precursors or cancer. In the study, researchers compared the screening performance of Pap tests and liquid-based cytology in terms of tests positivity rates, histological detection rates and positive predictive values (PPV). In the randomized control study, 89,784 women ages 30 to 60 who participated in the Dutch screening program at 246 family practice sites were included. One hundred twenty two practice sites were assigned to use the liquid-based cytology and screened 49,222 patients, and the other 124 practice sites were assigned to use the conventional pap test and screened 40,562 women. Subjects were screened for cervical intraepithelial neoplasms (CIN) and followed for 18 months.
Results showed that the adjusted detection rate ratio for CIN grade 1+ was 1.01; for CIN grade 2+ was 1.00, for CIN grade 3+ was 1.05; and for carcinoma was 1.69. “The adjusted positive predictive value ratios, considered at several cytological cutoffs and for various outcomes of CIN did not differ significantly from unity.” Further, “Because of the randomization, it can plausibly be assumed that the prevalence of CIN was equal in both groups. Therefore, the lack of difference in detection rates and PPV in this trial demonstrates that liquid-based cytology is neither more sensitive nor more specific in detecting cervical cancer precursors than the conventional Pap test.
