Triaging Pap cytology negative, HPV positive cervical cancer screening results with p16/Ki-67 Dual-stained cytology.

OBJECTIVE: Testing for human papillomavirus (HPV) has been shown to increase the sensitivity and negative predictive value for detection of high-grade cervical intraepithelial neoplasia (CIN2+), either when used in conjunction with Pap cytology testing or alone. However, there is no satisfying clinical management algorithm for women testing Pap negative/HPV positive. We therefore evaluated the clinical utility of a novel dual biomarker-based approach (p16/Ki-67 Dual-stained cytology) for the identification of CIN2+ in women with Pap negative/HPV positive screening results, without the need to refer all women to immediate colposcopy.
METHODS: All women aged ≥30 enrolled during 2007/2008 into a regional prospective Pap/HPV co-testing screening pilot project and tested Pap negative, but positive for HPV (n=425) were included in the analysis. p16/Ki-67 Dual-stained cytology was performed from residual cellular material available from the liquid-based cytology vial collected during the initial Pap/HPV co-testing screening visit. Results were correlated to the presence of CIN2+ confirmed during preliminary follow-up.
RESULTS: p16/Ki-67 Dual-stained cytology tested positive at baseline in 108 out of 425 (25.4%) Pap negative/HPV positive cases. Sensitivity of Dual-stain testing for the detection of biopsy-confirmed CIN2+ during preliminary follow-up within the group of Pap negative/HPV positive women was 91.9% for CIN2+ (34/37 cases), and 96.4% for CIN3+ (27/28 cases). Specificity was 82.1% for CIN2+ on biopsy, and 76.9% for CIN3+, respectively.
CONCLUSIONS: Triaging Pap negative/HPV positive screening test results with p16/Ki-67 Dual-stained cytology may identify women with a high probability of underlying CIN2+ and may efficiently complement HPV-based screening programs to prevent cervical cancer.