Human Papillomavirus Detection and Abnormal Anal Cytology in HIV-infected Patients Using p16/Ki-67 Dual-Staining

Evaluation of dual p16/Ki-67 immunostaining on anal cytology specimens

INTRODUCTION

Dual immunostaining for p16/Ki67 is FDA-approved for use on liquid-based cervical cytology specimens; however, the utility of dual staining in anal cytology especially for ASCUS risk stratification is not well established.

METHODS

We investigated dual staining performance on anal cytology specimens and correlated with subsequent cytologic interpretation, high-risk HPV status, and anal biopsy results. Dual staining for p16/Ki-67 was performed on all liquid-based anal cytology specimens from December 2021 to June 2022 (n = 43).

RESULTS

Three patients had high grade squamous intraepithelial lesion (HSIL/AIN2-3) on biopsy; dual staining was positive in all three cases. All HR-HPV negative cases were negative for dual staining. Among the 12 ASCUS samples with subsequent anal biopsy results all also had HR-HPV testing. Due to small sample size of cases with squamous intraepithelial lesion (SIL) diagnosed on biopsy, the sensitivity and positive predictive value was not calculated. However, the specificity and negative predictive value of p16/Ki-67 dual staining for SIL of any grade on biopsy were 1 (95% CI: 0.66-1) and 0.9 (95% CI: 0.65-0.97) respectively, whereas the specificity and negative predictive value of HR-HPV testing for SIL of any grade on biopsy were 0.44 (95% CI: 0.14-0.79) and 0.8 (95% CI: 0.41-0.96) respectively.

CONCLUSION

Dual p16/Ki-67 staining indicates transforming HPV infection and could help serve as an ancillary test for risk stratification for atypical anal cytology specimens. Among ASCUS samples, dual staining was specific for SIL of any grade with a high negative predictive value and therefore could be useful in clinical practices with limited availability for follow-up care.

Evaluation of HPV-Related Biomarkers in Anal Cytological Samples from HIV-Uninfected and HIV-Infected MSM

Men who have sex with men (MSM) harbor the highest risk for anal carcinoma, mainly caused by Human Papillomavirus (HPV). The use of HPV-related biomarkers in the screening for this neoplasia is still debated. We assessed the association between high-risk (hr)HPV DNA, HPV16/18 DNA, hrHPV E6/E7 mRNA, and p16/Ki-67 with cytological abnormalities (any grade) and high-grade intraepithelial lesions (HSIL) in HIV-uninfected and HIV-infected MSM. Overall, 150 cytological samples in PreservCyt (Hologic), with a negative to HSIL report, were analyzed for hrHPV DNA, hrHPV E6/E7 mRNA, and p16/Ki-67 using the Linear Array (Roche), Aptima (Hologic), and CINtec^® PLUS (Roche) assays. In HIV-infected MSM, positivity for all the biomarkers significantly increased with the cytological grade. In both populations, the association of hrHPV E6/E7 mRNA and p16/Ki-67 positivity with HPV16 did not differ significantly compared to hrHPVs other than HPV16. In HIV-uninfected MSM, the odds of having an HSIL increased approximately six times for the p16/Ki-67 positive cases. In HIV-infected individuals, all the biomarkers showed a significant association with HSIL, except for hrHPV DNA, with the strongest association observed for p16/Ki-67. The odds of HSIL increased almost 21 times in those positive for this biomarker. Our results encourage further investigation on the use of p16/Ki-67 dual staining in anal cancer screening for HIV-uninfected and HIV-infected MSM.