p16/Ki-67 dual-stained cytology for detecting cervical (pre)cancer in a HPV-positive gynecologic outpatient population

Women who test positive for a high-risk type of the human papillomavirus (HPV) require triage testing to identify those women with cervical intraepithelial neoplasia grade 3 or cancer (>= CIN3). Although Pap cytology is considered an attractive triage test, its applicability is hampered by its subjective nature. This study prospectively compared the clinical performance of p16/Ki-67 dual-stained cytology to that of Pap cytology, with or without HPV16/18 genotyping, in high-risk HPV-positive women visiting gynecologic outpatient clinics (n=446 and age 18-66 years). From all women, cervical scrapes (for Pap cytology, HPV16/18 genotyping, and p16/Ki-67 dual-stained cytology) and colposcopy-directed biopsies were obtained. The sensitivity of p16/Ki-67 dual-stained cytology for >= CIN3 (93.8%) did neither differ significantly from that of Pap cytology (87.7%; ratio 1.07 and 95% confidence interval (CI): 0.97-1.18) nor from that of Pap cytology combined with HPV16/18 genotyping (95.1%; ratio 0.99 and 95% CI: 0.91-1.07). However, the specificity of p16/Ki-67 dual-stained cytology for >= CIN3 (51.2%) was significantly higher than that of Pap cytology (44.9%; ratio 1.14 and 95% CI: 1.01-1.29) and Pap cytology combined with HPV16/18 genotyping (25.8%; ratio 1.99 and 95% CI: 1.68-2.35). After exclusion of women who had been referred because of abnormal Pap cytology, the specificity of p16/Ki-67 dual-stained cytology for >= CIN3 (56.7%) remained the same, whereas that of Pap cytology (60.3%) increased substantially, resulting in a similar specificity of both assays (ratio 0.94 and 95% CI: 0.83-1.07) in this sub-cohort. In summary, p16/Ki-67 dual-stained cytology has a good clinical performance and is an interesting objective microscopy-based triage tool for high-risk HPV-positive women.