Should we use risk selection tests for HPV 16 and/or 18 positive cases: Comparison of p16/Ki67 and cytology.

Major screening abnormalities in precolposcopic stage are tests results that imply direct referral to colposcopy (and/or expedited treatment) without performing additional high-grade squamous intraepithelial lesions or worse (HSIL+) risk selection testing. Currently, both clinically validated HSIL+ risk selection tests, reflex cytology and reflex p16/Ki67 dual staining (DS), are being compared for use in primary human papillomavirus (HPV)-based screening to avoid possible overtreatment, but there is still no sufficient data available for their performance. Among 30 066 liquid-based cervical cancer screening tests results, a group of 332 women was selected with available high-risk types of HPV tests results with 16/18 limited genotyping, liquid-based cytology, DS, and histology results from standardized colposcopy with biopsy. In HPV 16/18+ cases, three triage approaches were retrospectively analyzed. Predictive values for detection of HSIL+ were calculated and number of colposcopies required in each strategy. Both triage models with DS used (reflex cytology followed by DS, and reflex DS alone in all cases) had significantly higher positive predictive value for HSIL+ than strategy with reflex cytology alone (44.2%/45.7% vs. 28.3%; p < 0.0001). In models with DS, less colposcopies were required (95/92 vs. 152) and less colposcopies were needed per HSIL+ detection (2.26/2.19 vs. 3.54). Only one HSIL+ case was missed in both triage models with DS incorporation. p16/Ki67 dual-stain may be an effective, alone or combined with cytology, triage test to detect HSIL+ in patients with major screening abnormalities in primary HPV-based cervical cancer screening. Performing cytology as the first triage test improves the strategy by enabling referrals to expedited treatment in selected cases.