Performance of p16INK4a immunocytochemistry as a marker of anal squamous intraepithelial lesions

A systematic review and meta-analysis of cytology and HPV-related biomarkers for anal cancer screening among different risk groups

To inform optimal approaches for detecting anal precancers, we performed a systematic review and meta-analysis of the diagnostic accuracy of anal cancer screening tests in different populations with elevated risk for anal cancer. We conducted a literature search of studies evaluating tests for anal precancer and cancer (anal intraepithelial neoplasia grade 2 or worse, AIN2+) published between January 1, 1997 to September 30, 2021 in PubMed and Embase. Titles and abstracts were screened for inclusion and included articles underwent full-text review, data abstraction and quality assessment. We estimated the prevalence of AIN2+ and calculated summary estimates and 95% confidence intervals (CI) of test positivity, sensitivity and specificity and predictive values of various testing strategies, overall and among population subgroups. A total of 39 articles were included. The prevalence of AIN2+ was 20% (95% CI, 17-29%), and ranged from 22% in men who have sex with men (MSM) living with HIV to 13% in women and 12% in MSM without HIV. The sensitivity and specificity of cytology and HPV testing were 81% and 62% and 92% and 42%, respectively, and 93% and 33%, respectively for cytology and HPV co-testing. AIN2+ risks were similar among those testing positive for cytology, HPV, or co-testing. Limited data on other biomarkers (HPV E6/E7 mRNA and p16/Ki-67 dual stain), suggested higher specificity, but lower sensitivity compared with anal cytology and HPV. Our findings provide important evidence for the development of clinical guidelines using anal cytology and HPV testing for anal cancer screening.

Anal human papilloma viral infection and squamous cell carcinoma: Need objective biomarkers for risk assessment and surveillance guidelines

High grade anal intraepithelial neoplasia due to human papilloma viral (HPV) infections is a precursor lesion for squamous cell carcinoma especially in high risk populations. Frequent examination and anal biopsies remain unpopular with patients; moreover they are also risk factors for chronic pain, scarring and sphincter injury. There is lack of uniform, surveillance methods and guidelines for anal HPV specifically the intervals between exam and biopsies. The aim of this editorial is to discuss the intervals for surveillance exam and biopsy, based on specific HPV related biomarkers? Currently there are no published randomized controlled trials documenting the effectiveness of anal screening and surveillance programs to reduce the incidence, morbidity and mortality of anal cancers. In contrast, the currently approved screening and surveillance methods available for HPV related cervical cancer includes cytology, HPV DNA test, P16 or combined P16/Ki-67 index and HPV E/6 and E/7 mRNA test. There are very few studies performed to determine the efficacy of these tests in HPV related anal pre-cancerous lesions. The relevance of these biomarkers is discussed in this editorial. Longitudinal prospective research is needed to confirm the effectiveness of these molecular biomarkers that include high risk HPV serotyping, P16 immuno-histiochemistry and E6/E7 mRNA profiling on biopsies to elucidate and establish surveillance guidelines.

The Accuracy of Anal Swab-Based Tests to Detect High-Grade Anal Intraepithelial Neoplasia in HIV-Infected Patients: A Systematic Review and Meta-analysis

Background

The incidence of high-risk human papillomavirus (HR-HPV)–induced anal cancer is increasingly problematic among HIV-positive patients. Anal cancer is preceded by precursor lesions, anal intraepithelial neoplasia (AIN). AIN detection requires high-resolution anoscopy, a cumbersome and time-consuming procedure. We aggregated evidence on anal swab–based tests to detect AIN in HIV-positive patients.

Methods

We searched MEDLINE and EMBASE for cross-sectional studies on AIN detection with anal cytology, HR-HPV DNA detection, HPV E6/E7 mRNA analysis, and P16INK4a and Ki-67 immunostaining. Summary estimates of sensitivity and specificity were calculated using bivariate logistic regression. Cytology was reported using the terms squamous intra-epithelial lesion (SIL) for AIN and high-grade SIL (HSIL) for high-grade AIN (HGAIN).

Results

We included 22 studies. Using cytology with a cutoff of any SIL to detect HGAIN, we detected a sensitivity of 82% (95% CI, 74%–87%) and specificity of 45% (95% CI, 44%–66%); with the cutoff of HSIL, the sensitivity was 44% (95% CI, 45%–67%) and the specificity was 79% (95% CI, 69%-87%). The sensitivity of HPV DNA to detect HGAIN was 91% (95% CI, 82%–95%) and the specificity was 27% (95% CI, 21%–33%). For MSM, the positive predictive value (PPV) of cytology with a cutoff of any SIL was 36% (95% CI, 23%–50%) and the negative predictive value (NPV) was 87% (95% CI, 78%–93%), whereas cytology with a cutoff of HSIL had a PPV of 62% (95% CI, 50%–73%) and an NPV of 78% (95% CI, 65%–87%). The PPV of HR-HPV DNA detection was 37% (95% CI, 20%–57%) and the NPV was 87% (95% CI, 79%–93%).

Conclusions

Given its sensitivity, cytology with a cutoff of any SIL could be considered as a triaging method, whereas cytology with a cutoff of HSIL had better specificity and could be used for quality assurance. HR-HPV DNA detection had poor specificity and PPV, making it unsuitable for triage.

Strategies for screening and early detection of anal cancers: A narrative and systematic review and meta-analysis of cytology, HPV testing, and other biomarkers

Anal cancer incidence and mortality have been increasing over the past decade. Although the incidence in the general population remains low, it is much higher in certain subgroups, including those living with human immunodeficiency virus and men who have sex with men. Approximately 90% of anal squamous cell cancers are caused by infection with carcinogenic human papillomavirus (HPV). Given the common etiology between anal and cervical carcinogenesis, screening for anal cancer has been proposed in certain high-risk populations using strategies adapted from cervical cancer prevention. In this review, the authors discuss important differences in anal and cervical cancer regarding the populations at risk, disease natural history, and clinical procedures and outcomes that need to be considered when evaluating strategies for anal cancer screening. They also performed a systematic review and meta-analysis of the performance of anal cytology, anal HPV testing, and various biomarkers for the detection of anal precancers and cancers. The implications of these performance estimates are summarized in the context of risk-based screening and management of anal precancers, and important research gaps are highlighted that need to be addressed to fully understand the benefits and harms of anal cancer screening. Cancer Cytopathol 2018. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

p16 immunostaining as a predictor of anal and cervical dysplasia in women attending a sexually transmitted infection clinic

BACKGROUND

Carcinogenesis caused by human papillomavirus (HPV) leads to over-expression of p16 protein. p16 may act as a marker of HPV integration with host genome and serve as a surrogate marker of HPV oncogenesis.

MATERIALS AND METHODS

A single center study of 75 women (35 HIV-positive and 40 HIV-negative women) was conducted. Anal and cervical specimens were obtained for cytology and p16 immunostaining.

RESULTS

The sensitivity of p16 to diagnose anal and cervical dysplasia was 50% and 58.8%, respectively, whereas specificity was 98.6% and 100%, respectively. Positive predictive value for anal and cervical was 75% and 100%, whereas negative predictive value was 95.8% and 89.2%, respectively. A strong relationship between the grade of dysplasia and intensity of p16 immunoscore was observed (Pearson correlation r = 0.666, P < 0.0001 and r = 0.496, P < 0.0001 for anal and cervical, respectively).

CONCLUSION

p16 immunostaining with greater specificity for high-grade lesions may improve the diagnostic accuracy, especially for high-grade lesions which have a high risk of progression to malignancy and thereby necessitate treatment.

Anal cytology and p16 immunostaining for screening anal intraepithelial neoplasia in HIV-positive and HIV-negative men who have sex with men: a cross-sectional study

Summary Akin to cervical cancer in sexually-active women, men who have sex with men (MSM) are predisposed to anal cancers, especially those with HIV co-infection. This cross-sectional study endeavored to assess the prevalence of anal dysplasia using Pap smears and p16 immunostaining amongst Indian MSM. A total of 31 consecutive HIV-positive and 34 HIV-negative MSM, from a cohort of sexually transmitted infection clinic attendees, underwent anal cytological evaluation with Pap smear and p16 staining. Chi square test and coefficient of correlation were used for comparison. Eighteen (27.7%) had abnormal anal cytology; increased in HIV-positive as compared to HIV-negative men (35% versus 20%, p = 0.180). Similarly, both low-grade (25.8% versus 17.6%) and high-grade lesions (8.3% versus 4.8%) were comparable in HIV-positive and HIV-negative group. Thirteen (20%) smears were p16-positive with a sensitivity and specificity for anal dysplasia of 72.3% and 100%, respectively. Anal cytology may be used to screen for anal dysplasia in MSM irrespective of HIV status. Furthermore, the addition of p16, with greater specificity for high-grade lesions, may improve diagnostic accuracy especially for high-grade lesions. A larger study to further corroborate these observations is warranted.

Relative accuracy of cervical and anal cytology for detection of high grade lesions by colposcope guided biopsy: a cut-point meta-analytic comparison

Background

We recently reported, using a receiver operating characteristic area metric, the first meta-analytic comparison of the relative accuracy of cervical and anal cytology in detecting moderate or severe histopathologic lesions by magnification directed punch biopsy. The aim of the present research was to meta-analytically examine cut-point specific operating characteristics (sensitivity, specificity) of cervical and anal cytology in detecting high grade squamous intraepithelial lesion (HSIL) histopathology by colposcope directed punch biopsy.

Methodology/Principal Findings

The primary eligibility requirement was availability of tabulated cytology (normal, atypical cells of unclear significance [ASCUS], low grade squamous intraepithelial lesion, HSIL or atypical squamous cells cannot rule out high grade [ASC-H]) and biopsy (<HSIL, ≥ HSIL) counts. Meta-analysis and meta-regression of diagnostic accuracy was performed with examination of study quality criteria and heterogeneity. Thirty-three cervical and 11 anal publications were eligible between 1990 and 2010. Meta-analytically cut-point analysis showed that using a cut-point of ASCUS the sensitivity in both settings is similar while anal cytology is less specific than cervical cytology (specificity [95% confidence interval] 0.33 [0.20–0.49] vs. 0.53[0.40–0.66], p = 0.04) for the detection of HSIL histopathology by colposcope directed punch biopsy.

Conclusions/Significance

Using a cytology cut-point of HSIL or ASC-H, anal cytology is less sensitive but comparably specific to cervical cytology. However, using a cut-point of ASCUS, differences in accuracy were of borderline significance.

The reporting of anal cytology and histology samples: establishing terminology and criteria

Our understanding of the human papillomavirus (HPV) related cytomorphology and histopathology of the anal canal is underpinned by our knowledge of HPV infection in the cervix. In this review, we utilise cervical reporting of cytological and histological specimens as a foundation for the development of standardised and evidence-based terminology and criteria for reporting of anal specimens. We advocate use of the Australian Modified Bethesda System 2004 for reporting anal cytology. We propose the use of a two-tiered histological reporting system for noninvasive disease – low-grade and high-grade anal intraepithelial neoplasia. These classification systems reflect current understanding of the biology of HPV and enhance diagnostic reproducibility. Biomarkers such as p16INK4A may prove useful in further improving diagnostic accuracy. Standardisation is important because it will increase the value of the data collected as Australian centres develop programs for screening for anal neoplasia.

Comparative accuracy of anal and cervical cytology in screening for moderate to severe dysplasia by magnification guided punch biopsy: a meta-analysis

Background

The accuracy of screening for anal cancer precursors relative to screening for cervical cancer precursors has not been systematically examined. The aim of the current meta-analysis was to compare the relative accuracy of anal cytology to cervical cytology in discriminating between histopathologic high grade and lesser grades of dysplasia when the reference standard biopsy is obtained using colposcope magnification.

Methods and Findings

The outcome metric of discrimination was the receiver operating characteristic (ROC) curve area. Random effects meta-analysis of eligible studies was performed with examination of sources of heterogeneity that included QUADAS criteria and selected covariates, in meta-regression models. Thirty three cervical and eleven anal screening studies were found to be eligible. The primary meta-analytic comparison suggested that anal cytologic screening is somewhat less discriminating than cervical cytologic screening (ROC area [95% confidence interval (C.I.)]: 0.834 [0.809–0.859] vs. 0.700 [0.664–0.735] for cervical and anal screening, respectively). This finding was robust when examined in meta-regression models of covariates differentially distributed by screening setting (anal, cervical).

Conclusions

Anal cytologic screening is somewhat less discriminating than cervical cytologic screening. Heterogeneity of estimates within each screening setting suggests that other factors influence estimates of screening accuracy. Among these are sampling and interpretation errors involving both cytology and biopsy as well as operator skill and experience.