Clinical validation of p16/Ki-67 dual-stained cytology triage of HPV-positive women: Results from the IMPACT trial

Triage strategies are needed for primary human papillomavirus (HPV)-based cervical cancer screening to identify women requiring colposcopy/biopsy. We assessed the performance of p16/Ki-67 dual-stained (DS) immunocytochemistry to triage HPV-positive women and compared it to cytology, with or without HPV16/18 genotyping. A prospective observational screening study enrolled 35 263 women aged 25 to 65 years at 32 U.S. sites. Cervical samples had HPV and cytology testing, with colposcopy/biopsy for women with positive tests. Women without cervical intraepithelial neoplasia Grade 2 or worse (>= CIN2) at baseline (n = 3876) were retested after 1 year. In all, 4927 HPV-positive women with valid DS results were included in this analysis. DS sensitivity for >= CIN2 and >= CIN3 at baseline was 91.2% (95% confidence interval [CI]: 86.8%-94.2%) and 91.9% (95% CI: 86.1%-95.4%), respectively, in HPV16/18-positive women and 83.0% (95% CI: 78.4%-86.8%) and 86.0% (95% CI: 77.5%-91.6%) in women with 12 "other" genotypes. Using DS alone to triage HPV-positive women showed significantly higher sensitivity and specificity than HPV16/18 genotyping with cytology triage of 12 "other" genotypes, and substantially higher sensitivity but lower specificity than using cytology alone. The risk of >= CIN2 was significantly lower in HPV-positive, DS-negative women (3.6%; 95% CI: 2.9%-4.4%), compared to triage-negative women using HPV16/18 genotyping with cytology for 12 "other" genotypes (7.4%; 95% CI: 6.4%-8.5%; P < .0001) or cytology alone (7.5%; 95% CI: 6.7%-8.4%; P < .0001). DS showed better risk stratification than cytology-based strategies and provided high reassurance against pre-cancers both at baseline and at 1-year follow-up, irrespective of the HPV genotype. DS allows for the safe triage of primary screening HPV-positive women.