HOT TOPICp16INK4a immunostaining in cytological and histological specimens from the uterine cervix: A systematic review and meta-analysis
Introduction
Since the Papanicolaou (Pap test) cytological screening for cervical precancerous lesions was introduced in the 1940s, there has been a significant reduction in the incidence and mortality from cervical cancer.1 However, the efficacy of the Pap test is hampered by high interobserver variability and high false negative and false positive rates that range between 20–30%2 and 5–70%3, respectively. Technical improvements of the Pap test such as the liquid based cytology (LBC) have not been shown to improve sensitivity or specificity for detection of high-grade cervical intraepithelial neoplasia (CIN) compared to the conventional cytology.4
The introduction of human papillomavirus (HPV) DNA testing in clinical practice raised hopes for further improvements in the efficacy of the primary screening, triage and post-treatment surveillance. Randomized clinical trials published recently have demonstrated that HPV testing can be efficiently integrated into primary screening, either as an adjunct to cytology or as a sole primary test.[5], [6] It has also been shown that HPV DNA testing can be used to triage women with equivocal cytological abnormalities7 and that it has a potential role in identifying women at risk of residual or recurrent disease after treatment for CIN.[8], 9 However, it fails in the triage of low-grade lesions9 and even if implemented as a primary screening test, it would be necessary to have a more disease specific triage marker to identify women that would need to undergo colposcopy. Furthermore, a single HPV DNA test although it could confirm infection by the virus, present in 99% of all cervical cancers10, it does not discriminate between transient and chronic infection. The discrimination between the two types of infection is crucial as it is the persistent infection that predisposes to progression to cervical neoplasia and not the transient one.11
Even the histological assessment of cervical biopsies that is often considered as the “gold standard”, can be significantly hampered by intra- and inter-observer variability.12 Novel markers applied on histological specimens could improve the identification of women with ambiguous results that require treatment.
Research nowadays is focused on the development of objective biomarkers that can distinguish transforming from productive HPV infections and predict disease severity. The cellular tumor suppressor protein p16INK4a (p16) has been identified as a biomarker for transforming HPV infections. Physiologically, p16 blocks the activity of cyclin-dependent kinases CDK4/6. In a transforming HPV infection the viral oncogenes E6 and E7 interfere substantially with apoptosis and cell cycle regulation. Most importantly, E7 disrupts the protein of retinoblastoma (pRb) from its binding to E2F transcription factor and thereby promotes cell cycle progression, a molecular switch that is usually activated by CDK4/6. Affected cells strongly express p16 to counteract the irregular cell cycle activation; however, since E2F is not released through CDK4/6 action, but by E7, p16 expression has no effect on cell cycle activation. Over time, p16 accumulates in the nucleus and cytoplasm of affected cells and can be detected by immunostaining.13
This review represents an attempt to collect, systematically present and analyse the existing evidence on possible clinical applications of p16 in cytological and histological samples from the uterine cervix.
Section snippets
Search strategy
We searched two electronic databases – MEDLINE and EMBASE – targeting reports published between January 1998 and September 2007. The search strategy used terms such as “cancer”, “dysplasia”, “SIL”, “CIN”, “cervix”, “p16” and “cyclin-dependent kinase”. The references of retrieved articles together with the proceedings of relevant conferences were hand-searched in order to identify other potentially eligible studies for inclusion in the analysis missed by the initial search or any unpublished
Results
The electronic search yielded 584 studies that were assessed for inclusion in the review. Of those, 97 were potentially eligible and subsequently scrutinized in full text (Fig. 1).
Discussion
The progress in the understanding of HPV-related cervical carcinogenesis promoted the evaluation of various biomarkers that could potentially improve the current methods of cervical cancer screening. The cyclin-dependent kinase inhibitor protein p16 is one of the most promising and most studied of these biomarkers.
Immunostaining for p16 can be easily applied in both cytology and histology specimens. However, assessment of its clinical applications is seriously hampered by lack of standardized
Conclusion
The very large majority of studies on p16 immunostaining focus on the correlation between the biomarker and the degree of cytological or histological abnormality. Only a few address specific clinical questions such as the role of p16 in primary cervical cancer screening, in the triage of equivocal or low-grade smears versus the HPV-DNA test and its role as a marker of progression risk in low-grade dysplastic lesions of the cervix uteri. Furthermore, the discrepancies in the interpretation of
Conflict of interest statement
None of the authors has any financial or personal relationships with other people or organisations that could inappropriately influence (bias) their work.
Funding sources
Marc Arbyn received funding from the Gynaecological Cancer Cochrane Review Collaboration (Bath, United Kingdom) and the European Commission (Directorate of SANCO, Luxembourg, Grand-Duchy of Luxembourg) through the ECCG (European Cooperation on development and implementation of Cancer screening and prevention Guidelines, IARC, Lyon, France).
References (115)
- et al.
The role of HPV DNA testing in the follow-up period after treatment for CIN: a systematic review of the literature
Cancer Treat Rev
(2004) - et al.
Clinical utility of HPV-DNA detection: triage of minor cervical lesions, follow-up of women treated for high-grade CIN: an update of pooled evidence
Gynecol Oncol
(2005) The Bethesda system for reporting cervical/vaginal cytologic diagnoses: a report of the 1991 Bethesda workshop
Hum Pathol
(1992)- et al.
Meta-analysis in clinical trials
Controlled Clin Trials
(1986) - et al.
Human papillomaviruses, expression of p16INK4a, and early endocervical glandular neoplasia
Hum Pathol
(2002) - et al.
Which test is a better strategy to determine the outcome of atypical glandular cell-categorized Pap smears? Immunocytochemical p16NK4a expression or human papillomavirus test-a retrospective cohort study
Gynecol Oncol
(2005) - et al.
Endocervical glandular lesions: a diagnostic approach combining a semi-quantitative scoring method to the expression of CEA MIB-1 and p16
Gynecol Oncol
(2006) - et al.
Absence of p15INK4B and p16INK4A gene alterations in primary cervical carcinoma tissues and cell lines with human papillomavirus infection
Gynecol Oncol
(1998) - et al.
The status of human papillomavirus and tumor suppressor genes p53 and p16 in carcinomas of uterine cervix from India
Gynecol Oncol
(1998) - et al.
Methylation of p16INK4A in primary gynecologic malignancy
Cancer Lett
(1999)
P16 overexpression and human papillomavirus infection in small cell carcinoma of the uterine cervix
Hum Pathol
Correlation between p14(ARF)/p16(INK4A) expression and HPV infection in uterine cervical cancer
Cancer Lett
The site of infection and ethnicity of the patient influence the biological pathways to HPV-induced mucosal cancer
Mod Pathol
P16 as a molecular biomarker of cervical adenocarcinoma
Am J Obstet Gynecol
Cervical adenoid basal tumors comprised of adenoid basal epithelioma associated with various types of invasive carcinoma: clinicopathologic features, human papillomavirus DNA detection, and P16 expression
Hum Pathol
IMP3 is a novel biomarker for adenocarcinoma in situ of the uterine cervix: an immunohistochemical study in comparison with p16INK4a expression
Mod Pathol
Expression of p16INK4a in Papanicolaou smears containing atypical squamous cells of undetermined significance from the uterine cervix
Gynecol Oncol
P16INK4a and p14ARF expression pattern by immunohistochemistry in human papillomavirus-related cervical neoplasia
Mod Pathol
La proteine p16INK4a: un marquer cytologique pour detecter les neoplasies intraepitheliales de haut grade du col uterin
Ann Pathol
Is p16INK4a expression more useful that human papillomavirus test to determine the outcome of atypical squamous cells of undetermined significance-categorized Pap smears? A comparative analysis using abnormal cervical smears with follow-up biopsies
Gynecol Oncol
Usefulness of combining testing for p16 protein and human papillomavirus (HPV) in cervical carcinoma screening
Gynecol Oncol
Expression status of p16 protein is associated with human papillomavirus oncogenic potential in cervical and genital lesions
Am J Path
P16INK4a expression correlates with degree of cervical neoplasia: a comparison with Ki-67 expression and detection of high-risk HPV types
Mod Pathol
P16INK4a as a complementary marker of high-grade intraepithelial lesions of the uterine cervix. I: Experience with squamous lesions in 189 consecutive cervical biopsies
Pathology
Human papillomavirus genotyping and p16INK4a expression in cervical intraepithelial neoplasia of adolescents
Mod Pathol
Cell cycle and/or proliferation markers: what is the best method to discriminate cervical high-grade lesions?
Hum Pathol
Expression of p16INK4a in relation to histopathology and viral load of “high-risk” HPV types in cervical neoplastic lesions
Eur J Cancer
Natural history of cervical intraepithelial neoplasia: a critical review
Int J Gynecol Pathol
Meta-analysis of Pap test accuracy
Am J Epidemiol
Toward objective quality assurance in cervical cytopathology: correlation of cytopathologic diagnoses with detection of high-risk human papillomavirus types
Am J Clin Pathol
Liquid compared with conventional cervical cytology. A systematic review and meta-analysis
Obstet Gynecol
Human papillomavirus and Papanicolaou tests to screen for cervical cancer
N Engl J Med.
Human papillomavirus testing and liquid-based cytology: results at recruitment from the new technologies for cervical cancer randomized controlled trial
J Natl Cancer Inst
Virologic versus cytologic triage of women with equivocal Pap smears: a meta-analysis of the accuracy to detect high-grade intraepithelial neoplasia
J Natl Cancer Inst
Human papillomavirus is a necessary cause of invasive cervical cancer worldwide
J Pathol
Natural history of cervicovaginal papillomavirus infection in young women
N Eng J Med
Atypical squamous cells of undetermined significance-low-grade squamous intraepithelial lesion triage study (ALTS) group. Interobserver reproducibility of cervical cytologic and histologic interpretations: realistic estimates from the ASCUS-LSIL triage study
JAMA
Biomarkers in cervical cancer screening
Dis Markers
European guidelines for quality assurance in cervical cancer screening: recommendations for cervical cytology terminology
Cytopathology
Cervical intraepithelial neoplasia
Pathol Annu
The combination of estimates from different experiments
Biometrics
Overexpression of p16INK4a as a specific marker for dysplastic and neoplastic epithelial cells of the cervix uteri
Int J Cancer
Immunohistochemical staining with MIB1, bcl2 and p16 assists in the distinction of cervical glandular intraepithelial neoplasia form tubo-endometrial metaplasia, endometriosis and microglandular hyperplasia
Histopathology
P16INK4a is a useful marker for the diagnosis of adenocarcinoma of the cervix uteri and its precursors
Am J Surg Pathol
P16INK4a positivity in benign, premalignant and malignant cervical glandular lesions: a potential diagnostic problem
Virchows Archive
Expression of p16INK4a in Pap Smears containing atypical glandular cells from the uterine cervix
Acta Cytol
Evaluation of p16INK4a and pRb expression in cervical squamous and glandular neoplasia
Hum Pathol
Utility of p16INK4a, CEA, Ki67, P53 and ER/PR in the differential diagnosis of benign, premalignant, and malignant glandular lesions of the uterine cervix and their relationship with Silverberg scoring system for endocervical glandular lesions
Int J Gynecol Pathol
Alterations of CDKN2 (MTS1/p16INK4A) gene in paraffin-embedded tumor tissues of human stomach, lung, cervix and liver cancers
Exp Mol Med
The prognostic impact of cyclin dependent kinase inhibitors p21WAF1, p27Kip1, and p16INK4/MTS1 in adenocarcinomas of the uterine cervix: an immunohistochemical evaluation of expression patterns in population-based material from 142 patients with international federation of gynecology and obstetrics stage I and II adenocarcinoma
Cancer
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