Multicenter direct to vial evaluation of a liquid-based Pap test

Objective. To estimate the efficacy of a fluid-based, thin-layer preparation (TP) compared with the conventional Pap (CP) test to detect biopsy confirmed precancerous cervical lesions. Materials and Methods. A total of 10,226 evaluable patients at 10 separate clinical sites were screened for cervical abnormalities using the TP (ThinPrep pap test; Cytyc Corporation, Boxborough, MA). Results were compared with an historical control cohort of 20,918 patients from a similar patient population and with a similar patient profile who had received CP screening. Results. The TP significantly increased the detection rate of high-grade squamous intraepithelial lesion and more severe (HSIL+) cytologic results as compared with the CP smear. Overall, the TP method yielded a 59.7% increase in the detection of HSIL+ compared with the CP smear. Overall, the TP method yielded a 59.7% increase in the detection of HSIL+ compared with the conventional method (3.9% vs. 2.4%; p < .001). There was also a significant increase in the detection of low-grade squamous intraepithelial lesions with TP (p < .01). The rates of cancer, atypical squamous cells of undetermined significance, and atypical glandular cells of undetermined significance were similar for the TP and CP groups. Conclusions. The overall cytologic detection of HSIL and low-grade squamous intraepithelial lesions with the TP method was significantly increased compared with a control group screened with the CP method. Histologic confirmation showed increased detection, not an increased false-positive cytologic interpretation.