Optimization of HPV-positive women triage with p16/Ki67 dual staining cytology in an organized cervical cancer screening program in the center region of Portugal

Background: Organized cervical cancer (CxCa) screening is the most effective secondary prevention method to decrease the disease incidence and mortality. Screening for infection with 14 high-risk HPV genotypes (hrHPV) is recommended as primary screening test. Since only ca. 6 % of HPV-positive (HPV+) women will develop a high-grade lesion in 5 years, triage is critical for risk stratification and management of colposcopy resources. Dual staining (DS) p16/Ki67 cytology is an alternative to Papanicolau cytology (PAP) for triage of HPV+women, with potential improvements in sensitivity and specificity, and optimization of colposcopy referrals. Objectives: To compare PAP vs DS cytology in terms of (i) optimization of referrals for colposcopy and (ii) risk stratification to better define the follow-up interval. Study design: Retrospective analysis of the CxCa screening database of Centro Hospitalar Universit & aacute;rio de Coimbra (CHUC), one of the centralized diagnostic laboratories for the CxCa screening program of the central region of Portugal, between July 2019 and May 2023. At CHUC, since July 2019, all samples from hrHPV+women have been triaged with liquid PAP and tested with DS cytology. Results: At baseline (1032 HPV+women), 1028 women were tested with DS: 739 women were DS negative (DS-) [70.7 % with normal PAP cytology (NILM) and 29.3 % with abnormal PAP cytology (ASC-US+)], and 289 were DS positive (DS+) (1.1 % NILM and 98.6 % ASC-US+). DS positivity as referral criterion for colposcopy instead of ASC-US+would have reduced the number of colposcopies by 39.4 % overall and by 48.3 % for other 12 hrHPV, while improving the number of colposcopies per HSIL (3.9 vs. 2.4 overall and 4.9 vs. 2.9 for other 12 hrHPV). In this cohort, if the follow-up interval for women positive for other 12 hrHPV+and DS- would have been extended from 1 to 3 years, 799 follow-up consultations, 799 HPV re-tests, and 277 colposcopies (-64.7 %) would have been avoided, with an overall risk of missed HSIL lesions of 2.2 %. Conclusions: Triage with DS allows the optimization of colposcopy referrals and a safe extension of the follow-up interval to 3 years for other 12 hrHPV+/DS- women, eliminating the need for annual re-testing for many women.