ORIGINAL ARTICLE Ki-67 immunocytochemistry in liquid based cervical cytology: useful as an adjunctive tool?

Aims: To test the ability of Ki-67 to detect cytological lesions in a screening setting and its use as a sur-rogate marker of human papillomavirus (HPV) infection. Methods: A study of liquid based cytology, HPV DNA testing by MY09/MY11 consensus polymerase chain reaction (PCR), type specific PCRs, and Ki-67 immunocytochemistry on a randomly selected series of 147 patients. Results: Comparison of the number of Ki-67 immunoreactive cells/1000 cells in the different cytologi-cal groups showed that the HSIL group yielded a significantly higher mean count than did the other groups. The number of Ki-67 immunoreactive cells/1000 cells was significantly higher in HPV-16 posi-tive samples than in samples containing infections with other high risk types. Receiver operating char-acteristic curves indicated a test accuracy (area under curve) of 0.68, 0.72, and 0.86 for atypical squamous cells of undetermined significance (ASCUS), low grade squamous intraepithelial lesions (LSIL), and high grade squamous intraepithelial lesions (HSIL), respectively. Thresholds for 95 % sensi-tivity were 0.07, 0.08, and 0.15 Ki-67 immunopositive cells/1000 cells for ASCUS, LSIL and HSIL, respectively. The threshold for 95 % specificity was 1.9 Ki-67 immunopositive cells/1000 cells. Conclusions: Ki-67 immunocytochemistry can be applied to liquid based cytology. The accuracy an