Predictive Value of Marker of Proliferation Ki-67 and Cell Cycle Dependent Protein kinase Inhibitor P16INK4a in Cervical Biopsy to Determine Its Biological Behaviour

Objective: The aim of the study is to analyse the Immuno-histochemical expression of   Ki-67  and P16INK4a in CIN and cervical cancer cases  and  their utility to determine the accuracy of histological diagnosis and prediction of biological behavior of cervical lesion. Methodology: A retrospective cross-sectional study was carried in 110 numbers of cervical biopsy that included 25 CIN1, 21 CIN2, 12 CIN3, 26 SCC and 01 adenocarcinoma and 25 non neoplastic lesion. The tissue sections were stained with Ki-67 and P16INK4a. Results: Ki-67 expression was seen in 55.5% (61/110) cases of cervical lesion., out of which 3.6% (4/110; cervicitis -2/110 and metaplasia-2/110) cases were non dysplaia, 51.8% (57/110) cases were dysplasia /CIN of varying grade including invasive cancer. P16INK4a expression was noted 51.8% (57/110). There was an increasing trend of the intensity of Ki-67 and P16INK4a from focal positivity in low grade lesion to diffuse intensity in higher grade lesion and is statistically significant. There was strong association between the two variables Ki-67 and P16INK4a positive cases with their histologic grade. Conclusion: Though histopathology remains the ‘‘gold standard’’ for the diagnosis of CIN, both low and high-grade, biomarkers like Ki-67 and P16INK4a have emerged as helpful adjuncts. Their combined use may assist in the histopathologic classification of preinvasive lesions and facilitate the distinction from nondysplasia.     

p16INK4A immunohistochemical staining and predictive value for progression of cervical intraepithelial neoplasia grade 1: A prospective study in China

p16^INK4A is strongly expressed in tissues diagnosed as cervical intraepithelial neoplasia (CIN) and cancer in women infected with human papillomavirus (HPV), but few prospective studies have evaluated p16^INK4A as a marker for the risk of low‐grade CIN (CIN1) progression. We investigated the prevalence of p16^INK4A immunostaining by CIN grade and whether overexpression of p16^INK4A in CIN1 predicts future risk for high‐grade CIN in Chinese women. 6,557 Chinese women aged 30–49 years were screened from 2003 to 2005 using cytology and carcinogenic HPV test. Colposcopy was performed on women with any abnormal result. p16^INK4A Immunostaining was performed on biopsies from all women with CIN1, as well as randomly selected women with normal or CIN grade 2 and worse (CIN2+) biopsies. Women with CIN1 were followed up without treatment. Colposcopy was performed on all untreated women at a 2‐year interval. The prevalence of p16^INK4A staining was 2.7%, 42.7%, 75.5%, 79.6% and 100% among women with normal, CIN1, 2, 3 and cancer biopsies, respectively (p < 0.001). HPV positivity was strongly associated with p16^INK4A staining [odds ratios (OR) = 12.8; 95% confidence intervals (CI): 5.2–31.6]. p16^INK4A staining of CIN1 biopsies at baseline was associated with an increased risk of finding high‐grade CIN over 2 years of follow‐up (OR = 1.43; 95% CI: 0.52–3.91). The two‐year cumulative incidence of CIN2+ for p16^INK4A positive women was higher at 10.71% than for p16^INK4A negative women at 1.30% (crude RR = 8.25, 95% CI: 1.02–66.62). p16^INK4A overexpression is strongly associated with grade of CIN and risk of progression to high‐grade CIN in women with low‐grade lesions.     

Evaluation of p16INK4a expression in ThinPrep cervical specimens with the CINtec p16INK4a assay: correlation with biopsy follow-up results

BACKGROUND: The aim of this study was to examine p16(INK4a) protein expression in ThinPrep (Cytyc Corporation, Marlborough, Mass) cervical specimens by using the CINtec p16(INK4a) Cytology Kit (Dako, Glostrup, Denmark). The ability of this assay to accurately identify underlying high-grade lesions was assessed by using follow-up biopsies and comparing these results with Hybrid Capture 2 (Digene, Gaithersburg, Md) high-risk HPV (hc(2)) results. METHODS: Three hundred ninety-eight residual ThinPrep samples were collected, and histological follow-up data were retrieved for abnormal cytology specimens. After preparation of a Papanicolaou-stained slide, a second slide was processed in preparation for p16(INK4a) immunostaining. High-risk human papillomavirus testing (hc(2)) was also performed. RESULTS: Of the 163 cytologically abnormal samples, 6-month biopsy follow-up data were available for 45% of the specimens. At initial blinded evaluation, 21 of the 26 cases with cervical intraepithelial neoplasia (CIN) II/III follow-up were positive for p16(INK4a), yielding an overall diagnostic sensitivity of 81%; 29 of the 47 cases diagnosed as CIN I or less were p16(INK4a) negative, yielding a diagnostic specificity of 62%. In comparison, the hc(2) test results indicated a diagnostic sensitivity of 100% with a diagnostic specificity of 15%. After review of selected cases with CIN II/III follow-up, 25 of 26 slides were deemed to be positive for p16(INK4a), increasing the diagnostic sensitivity to 96%. CONCLUSIONS: The CINtec p16(INK4a) Cytology Kit, in combination with ThinPrep cervical samples, allowed clear evaluation of p16(INK4a) protein overexpression. Diagnostic specificity of the CINtec p16(INK4a) assay was significantly improved relative to hc(2). To increase p16(INK4a) immunostaining in abnormal cells, a modified kit version with improved staining performance has been developed and is currently being evaluated.     

p16(INK4a) immunocytochemistry in liquid-based cervical cytology: is it feasible for clinical use?

A consecutive series of 118 samples from patients referred to colposcopy assessment and follow-up with cytology and biopsies were analysed with immunocytochemical staining to determinate the expression of p16(INK4a). Accumulation of p16(INK4a) antigen has been proposed as a biomarker helpful for the identification of dysplastic cervical cells. In our study all benign cases were negative for p16(INK4a), while more than half of the high grade lesions showed moderate or strong reactivity. There was a correlation between CIN grade and p16(INK4a) expression levels with more advanced lesions showing stronger reactivity. The correlation between p16(INK4a) immunoreactivity and the severity of cytological abnormality was stronger, when the diagnosis was based on simultaneous routine cytology (p<0.001, chi(2) exact test for trend). There was no or weak reactivity in benign cases, as well as almost all low-grade lesions, while two thirds of high-grade lesions showed moderate or strong staining for p16(INK4a) antigen. Thus p16(INK4a) expression analysis yielded information which is consistent with results from the histopathology and is a simple way of emphasizing the presence of premalignant cell reactive atypias. This staining can be applied to cytological samples, and might be a complement prognostic procedure in order to find women at risk for cervical cancer.     

Evaluation of cervical cone biopsies for coexpression of p16INK4a and Ki-67 in epithelial cells

Diffuse overexpression of p16(INK4a) in basal and parabasal cells of cervical epithelium is a hallmark of human papillomavirus-mediated transformation. Focal p16(INK4a) expression is occasionally observed in nondysplastic epithelium. In normal cells, expression of p16(INK4a) triggers cell cycle arrest. However, cells undergoing transformation in intraepithelial lesions actively proliferate. To prove that the different expression patterns of p16(INK4a) , i.e., focal versus diffuse, reflect biologically different entities, we hypothesized that p16(INK4a) -positive cells in epithelia displaying focal p16(INK4a) expression pattern do not coexpress proliferation-associated Ki-67 protein, while p16(INK4a) -positive cells in lesions with diffuse p16(INK4a) expression may do. A total of 138 cervical cone biopsies were stained for the expression of p16(INK4a) and Ki-67 using a primary antibody cocktail. All metaplastic lesions (n = 21) displayed focal staining for p16(INK4a) , and in all of these lesions p16(INK4a) -positive cells were found to be negative for Ki-67 expression. Diffuse expression of p16(INK4a) was observed in 12/21 (57.1%) cervical intraepithelial neoplasia (CIN) 1 lesions, all of them simultaneously showed Ki-67 immunoreactivity in a large proportion of p16(INK4a) -positive cells. Seventeen of 23 (73.9%) CIN2 lesions and all 27 (100%) CIN3/carcinoma in situ (CIS) as well as all 46 (100%) carcinoma cases displayed diffuse and combined expression of p16(INK4a) and Ki-67. Coexpression of Ki-67 and p16(INK4a) in the same cell is entirely restricted to cervical lesions displaying diffuse p16(INK4a) expression, whereas in lesions with focal p16(INK4a) expression, p16(INK4a) -expressing cells are negative for Ki-67. Thus, diffuse expression of p16(INK4a) reflects lesions with proliferation-competent cells, while p16(INK4a) -expressing cells associated with focal expression patterns are cell cycle arrested.     

Expression of p16(INK4a) in relation to histopathology and viral load of 'high-risk' HPV types in cervical neoplastic lesions

A total of 91 cervical archival biopsy series were analysed for the presence and viral load of 'high-risk' types of human papillomavirus (HR-HPV), and p16(INK4a) expression. The women had various degrees of CIN (cervical intraepithelial neoplasia). HPV 16 was the most prevalent type found, at 47% frequency. The frequency of HPV 16 increased with increasing immunoreactivity to p16(INK4a), from 39% to 44% at cases scored low to medium, to 65% at high reactivity. Thirty (33%) of the samples had negative p16(INK4a) analysis results, but were positive for HR-HPV. There was no significant correlation between viral load and the level of p16(INK4a) expression, while the grade of CIN correlated to such expressions. Thus, p16(INK4a) expression analysis yielded information which is consistent with results from the histopathology and might complement the HPV analysis in a clinical prognostic procedure in order to find women at risk for cervical cancer.     

Immunohistochemical evaluation of heat shock proteins in normal and preinvasive lesions of the cervix

Heat Shock Proteins (HSPs) are molecular chaperons with multiple functions relating to cellular homeostasis. Primary, HSPs are expressed in response to cellular stresses that may also include carcinogenesis. Patterns of expression have not been extensively evaluated in the multi-step carcinogenesis of cervical cancer (Normal --> HPV infection --> Cervical Precancer --> Cancer). We evaluated the expression of HSP40, HSP60, HSP70, and HSP90 in normal tissues (N=30), in cervical intraepithelial neoplasia grade 1 (CIN1)(synonymous with productive HPV infections) (N=32), and in CIN3 (cervical precancer)(N=25) by immunohistochemistry staining (graded 0-3) and compared the results to p16INK4a, a biomarker of oncogenic HPV infections and CIN3. We found strong patterns of increased HSP40, HSP60, and HSP70 immunostaining with increasing severity of the lesion in a manner similar to p16INK4a (P(Trend)<0.0005). No difference in staining intensity by grade of lesion was observed for HSP90 (P(Trend)=0.8). Tissue patterns in CIN3 of diffuse immunostaining for HSP40 and HSP70 were analogous to those observed for p16INK4a; HSP60 immunostaining appeared more punctate within cells than for other antigens although similar tissue patterns were observed. We conclude that HSP40, HSP60, and HSP70 expressions are up-regulated in response to the development of CIN3 akin to p16INK4a expression.     

Predictive significance of the alterations of p16INK4A, p14ARF, p53, and proliferating cell nuclear antigen expression in the progression of cervical cancer.

PURPOSE: The purpose of this research was to evaluate the clinical significance of p16INK4A, p14ARF, p53, and proliferating cell nuclear antigen (PCNA) expression in tumor progression of cervical cancer. DESIGN: Seventeen patients (40 samples) with consecutive cervical lesions from normal squamous epithelium, inflammation of the cervix to cervical intraepithelial neoplasm (CIN) and invasive cervical squamous cell cancer (SCC), or from CIN to SCC were collected for this study. Expression of p16INK4A, p14ARF, p53, and PCNA were detected by immunohistochemistry on paraffin-embedded sections. Human papillomavirus DNA was detected simultaneously with PCR and typed according to its DNA sequence. RESULTS: p16INK4A overexpression was significantly higher in CIN (75%) and in SCC (75%) than in normal or inflammation of the cervix (12.5%; P < 0.01, P < 0.05, respectively). The positive rate of p14ARF expression was higher in SCC (83%) than in normal/inflammation of the cervix (25%; P < 0.05). PCNA expression was negative in normal or inflammation of the cervix, but an increased in expression was seen in 63.2% in CIN and 100% in SCC (P < 0.01, P < 0.05). When the time interval for disease progression from initial biopsy to CIN 3 or invasive cancer was compared with states of p16INK4A expression, cases stained positive for p16INK4A progressed within 64.2 months as compared with 122.3 months among those stained negatively (P < 0.01). Cases with increased p14ARF expression also had a short time interval for disease progression of 78.8 months as compared with 108.3 months in cases that were p14ARF negative. Cases with stable or decreased p53 expression had the shortest time interval for progression of 32.3 months in contrast to cases with no p53 expression (113.9 months). However, cases with increasing p53 expression progressed within 60.8 months. CONCLUSIONS: Our results suggested that altered states of p16INK4A, p14ARF, p53, and PCNA may be valuable markers to predict the progression of cervical neoplasia.     

The Association of Molecular Biomarkers in the Diagnosis of Cervical Pre-Cancer and Cancer and Risk Factors in Senegalese

Background: Cervical intraepithelial neoplasia (CIN) grading is subjective and affected by substantial rates of discordance among pathologists. Although recent studies have suggested that p16INK4a may be a useful surrogate biomarker of cervical neoplasia, Ki-67 and human papillomavirus testing have also been shown to be useful in detecting neoplasia. The purpose of this study was to determine the expression of p16INK4a and Ki-67 in cervical neoplasia and its correlations with cofactors. Methods: The study involved 69 patients with and without cervical neoplasia who underwent colposcopic directed biopsy. On each patient, two samples were taken; the first was used for immunohistochemistry and the second for molecular testing, using HPV16and18 genotyping Real-Time PCR Kit. Results: The study revealed the expression level of p16INK4a and Ki-67 in a descending order, from invasive squamous cell carcinoma (SCC), CIN2/3, CIN1 and non-dysplastic lesions. Correlations showed an association between the staining of p16NK4a and Ki-67 with the increase of age (OR: 1.79 (95%IC: 0.49 – 6.55), p = 0.037) and marital status (OR: 0.17 (95%IC: 0.04 – 0.68), p = 0.003). We found that the expressions of p16INK4a and Ki-67 were significantly different between invasive SCC vs non-dysplasia (OR: 44.57 (95%IC: 4.91 – 403.91), p <0.0001). The study showed significant correlation between HPV 16and18 infection with p16 INK4a and Ki-67 expression (OR: 0.13 (95%IC: 0.03 – 0.52), p <0.0001). Strong expression of p16INK4a and Ki-67 were observed in invasive squamous cell carcinoma, moderate staining was found in CIN2/3, weak staining in CIN1 and normal histology. Conclusion: Our findings indicate that p16INK4a and Ki-67 expressions associated strongly with cervical pathology. Therefore, p16/Ki-67 could be considered as a suitable biomarker for cervical cancer screening, particularly in HPV-based screening programs.     

p16INK4a and laminin-5gamma2 chain expression during the progression of cervical neoplasia

p16INK4a, laminin-5gamma2 chain, and PCNA were investigated to compare the expression levels in relation to histological diagnosis and time for progression. The material consisted of 37 normal cervical tissues, 35 with different grades of CIN, and 11 invasive cervical cancers. Our results showed a reduction of basement membrane staining for laminin-5gamma2 chain from 78.4% in normal squamous epithelium to 27.8% in CIN3 (p < 0.001). The intracytoplasmic staining for laminin-5gamma2 chain increases with severity of lesion. The same trend was observed with p16INK4a and PCNA expression (p < 0.001). Co-expression of p16INK4a and PCNA was seen in 85.7% of samples. Cases that were laminin-5gamma2 chain BM - /p16INK4a+/PCNA+ have the shortest interval time (average: 46.8+/-36.3 months) for progression, while cases with laminin-5gamma2 chain BM + /p16INK4a-/PCNAPCNA--have the longest time interval (average: 110.2+/-52.7 months) (p < 0.05). Thus co-expression of p16INK4a, laminin-5gamma2 chain and PCNA may be valuable for the prediction progression of cervical neoplasia.     

Immunocytochemical colocalization of P16(INK4a) and Ki-67 predicts CIN2/3 and AIS/adenocarcinoma

BACKGROUND:

Although previous studies have shown that p16^INK4a and Ki‐67 are sensitive and specific markers for high‐grade lesions (≥CIN2) on cervical biopsies, limited information is available regarding the performance of a dual‐staining approach as a diagnostic adjunct in cervical cytology. We evaluated a dual p16^INK4a/Ki‐67 immunocytochemistry (ICC) assay to determine its sensitivity and specificity versus that of high‐risk HPV (HR‐HPV) in a US‐based pilot cytology study.

METHODS:

ThinPrep specimens from 122 cervical cytology specimens encompassing 23 negative (NILM), 20 ASC‐US, 22 LSIL, 17 ASCH, 22 HSIL, and 18 AGC cases were processed for multiplexed ICC staining using a CINtec Plus Kit. Dual‐positive assay results were defined based on the detection of 1 or more epithelial cells that were stained for both p16^INK4a and Ki‐67 without regard to cellular morphology. HR‐HPV testing was performed by multiplex PCR with capillary electrophoresis genotyping.

RESULTS:

Dual staining for p16^INK4a and Ki‐67 was frequently detected in HSIL and AGC but was rarely detected in NILM cases. The HR‐HPV assay showed a sensitivity of 76.2% and a specificity of 55.8% for the detection of clinically significant cervical squamous or endometrial lesions. In contrast, the colocalization of p16^INK4a plus Ki‐67 maintained a high sensitivity of 81.8% and improved specificity to 81.8% for biopsy‐confirmed CIN2/3, endocervical adenocarcinoma, or endometrial adenocarcinoma.

CONCLUSIONS:

Dual staining for p16^INK4a/Ki‐67 immunocytochemistry dramatically increased specificity and maintained high‐level sensitivity for the diagnosis of CIN2/3 or glandular lesions compared with PCR‐based testing for HR‐HPV. Cancer (Cancer Cytopathol) 2012. © 2011 American Cancer Society.     

Combined p16INK4a and human papillomavirus testing improves the prediction of cervical intraepithelial neoplasia (CIN II-III) in Thai patients with low-grade cytological abnormalities

Thailand is in the process of developing a national cervical screening program. This study examined p16INK4a staining and HPV prevalence in abnormal cervical samples with atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesion (LSIL), to evaluate the efficacy of combined HPV and p16INK4a detection to predict CIN II-III. Totals of 125 ASCUS and 87 LSIL cases were re-evaluated by Pap test and cervical cells of ASCUS and LSIL cases were prepared on slides for p16INK4a detection by immunocytochemistry. HPV genotyping of DNA extracts was performed by GP5+/6+ PCR and reverse line blot hybridization. Histopathologic tests were performed to identify cervical lesion. Total of 212 cases were diagnosed to normal (20), ASCUS (112), LSIL (78) and HSIL (2). HPV was detected in ASCUS (49/112, 43.8%), LSIL (60/78, 76.9%) and HSIL (2/2, 100%) cases. The majority of HPV positive samples typed for high-risk HPV. 55.7% (107/192) of abnormal cases (ASCUS, LSIL and HSIL) were positive p16INK4a. For the 111 HPV DNA positive cases, 34 of 49 (69.4%) ASCUS cases and 49 of 60 (81.7%) LSIL cases were p16INK4a positive. 140 biopsies were taken and histological classified: CIN negative (65 cases), CIN I (56 cases) and CIN II-III (19 cases). HPV DNA detection predicted CIN II-III with sensitivity and specificity of 84% and 49%, whereas p16INK4a staining showed higher sensitivity (89.5%) and specificity (56.2%). The prediction of CIN II-III was significantly better by combination of positive HPV DNA and p16INK4a with 93.8% sensitivity and 59.2% specificity. Detection of HPV DNA combined with p16INK4a in cervical cells can predict CIN II-III and may improve the screening diagnosis of Thai women at risk for CIN II-III or cancer.     

Evaluation of p16INK4a expression in ThinPrep cervical specimens with the CINtec p16INK4a assay

BACKGROUND.

The aim of this study was to examine p16^INK4a protein expression in ThinPrep (Cytyc Corporation, Marlborough, Mass) cervical specimens by using the CINtec p16^INK4a Cytology Kit (Dako, Glostrup, Denmark). The ability of this assay to accurately identify underlying high‐grade lesions was assessed by using follow‐up biopsies and comparing these results with Hybrid Capture 2 (Digene, Gaithersburg, Md) high‐risk HPV (hc₂) results.

METHODS.

Three hundred ninety‐eight residual ThinPrep samples were collected, and histological follow‐up data were retrieved for abnormal cytology specimens. After preparation of a Papanicolaou‐stained slide, a second slide was processed in preparation for p16^INK4a immunostaining. High‐risk human papillomavirus testing (hc₂) was also performed.

RESULTS.

Of the 163 cytologically abnormal samples, 6‐month biopsy follow‐up data were available for 45% of the specimens. At initial blinded evaluation, 21 of the 26 cases with cervical intraepithelial neoplasia (CIN) II/III follow‐up were positive for p16^INK4a, yielding an overall diagnostic sensitivity of 81%; 29 of the 47 cases diagnosed as CIN I or less were p16^INK4a negative, yielding a diagnostic specificity of 62%. In comparison, the hc₂ test results indicated a diagnostic sensitivity of 100% with a diagnostic specificity of 15%. After review of selected cases with CIN II/III follow‐up, 25 of 26 slides were deemed to be positive for p16^INK4a, increasing the diagnostic sensitivity to 96%.

CONCLUSIONS.

The CINtec p16^INK4a Cytology Kit, in combination with ThinPrep cervical samples, allowed clear evaluation of p16^INK4a protein overexpression. Diagnostic specificity of the CINtec p16^INK4a assay was significantly improved relative to hc₂. To increase p16^INK4a immunostaining in abnormal cells, a modified kit version with improved staining performance has been developed and is currently being evaluated. Cancer (Cancer Cytopathol) 2007. © 2007 American Cancer Society.     

p16INK4a免疫细胞化学检测在筛查宫颈癌中的作用

目的 探讨p16^INK4a免疫细胞化学检测在筛查宫颈癌及其癌前病变中的作用。方法 选择220例宫颈液基细胞学剩余标本,制作液基薄片进行p16^INK4a 免疫细胞化学检测,随访组织活检结果,并与高危人乳头瘤病毒（HR—HPV）DNA检测结果进行对照。结果 p16^INK4a在宫颈细胞学诊断的鳞状细胞癌（SCC）、鳞状上皮内高度病变（HSIL）、鳞状上皮内低度病变（LSIL）、非典型鳞状细胞-小除外上皮内高度病变（ASC—H）和非典型鳞状细胞-不能明确意义（ASC—US）病例的阳性表达率分别为100．0％（7／7）、92．2％（107／116）、24．3％（17／70）、100．0％（14／14）和36．4％（4／11）。150例p16^INK4a阳性者中,111例有组织活检诊断,其中宫颈上皮内瘤变（CIN）2级及以上病变者97例（87．4％）;70例p16^INK4a阴性者中,18例有组织活检诊断,无一例CIN2及以上病变。p16^INK4a在CIN2及以上病变与在CIN1之间的阳性表达率差异有统计学意义（P〈0.01）,而HR-HPV DNA的阳性率在两者之间差异无统计学意义。结论 p16^INK4a在宫颈HSIL及以上病变中高表达,有利于高危病例的筛选。     

P16INK4a及Ki-67免疫细胞化学检测对ASC-US中高级别病变检出的意义

目的：探讨液基细胞学剩余细胞标本P16INK4a、Ki-67免疫细胞化学染色检测宫颈癌前病变的价值。方法：选取2010年1月至2012年6月因宫颈疾病于北京大学第三医院妇产科就诊患者液基细胞学剩余标本50例。所有患者行高危型HPVDNA杂交捕获II代（HCII）检测,P16INK4a、Ki-67免疫细胞化学检测,同时行阴道镜检查及组织病理学活检。结果：以病理诊断将患者分为CIN2以下组和CIN2及以上组。CIN2及以上组P16INK4a及Ki-67表达量高于CIN2以下组,差异均具有统计学意义（P〈0．05）;P16INK4a或Ki-67检测对高级别病变预测的准确性在ASC—US组中优于异常细胞学组;在ASC—US中,P16INK4a或Ki-67检测对高级别病变预测的准确性优于高危型HPV检测。结论：宫颈脱落细胞中P16INK4a或Ki-67免疫细胞化学检测相比于高危型HPV检测可以提高对ASC—US中高级别病变的检出作用。     

Validation of p16INK4a as a marker of oncogenic human papillomavirus infection in cervical biopsies from a population-based cohort in Costa Rica.

Due to the high prevalence of cancer-associated types of human papillomavirus (HPV) and the poorly reproducible histologic classification of low-grade lesions, identifying infected women at highest risk for cancer prior to neoplastic progression remains a challenge. We therefore explored the utility of p16INK4a immunostaining as a potential diagnostic and prognostic biomarker for cervical neoplasia using paraffin-embedded tissue blocks (punch biopsies and loop electrosurgical excision procedures) obtained from women referred to colposcopy during the enrollment phase of the Guanacaste Project (1993 to 1994). All blocks from 292 women selected by HPV status (HPV negative, nononcogenic HPV positive, or oncogenic HPV positive) and representing the diagnostic spectrum of the population [normal to precancer: cervical intraepithelial neoplasia (CIN) 3] were immunostained for p16INK4a using the p16INK4a research kit based on the monoclonal antibody clone E6H4 (MTM Laboratories, Heidelberg, Germany). For CIN3, the sensitivity of diffuse p16INK4a immunostaining was 100% and the specificity was 95%. For CIN2, the sensitivity and specificity for diffuse staining were 81.1% and 95.4%, respectively. Generalized to the 10,000-woman cohort, this translated to positive predictive value and negative predictive value of 13.9% and 100% for CIN3, respectively, and 20.4% and 99.7% for CIN2 or CIN3, respectively. Of women with an initial diagnosis of less than CIN2 for whom follow-up data for up to 5 to 7 years were available, 44% with diffuse staining developed persistent infection (CIN2 or CIN3). Whereas our data support the diagnostic potential for p16INK4a, further prospective studies with detailed follow-up determining the prognostic capacity of this marker are needed.     

乳头瘤病毒L1衣壳蛋白及p16INK4A基因在子宫颈病变中的表达及其相关性

 目的　研究乳头瘤病毒衣壳蛋白（HPVL1）及p16INK4A基因在子宫颈病变患者中的表达与相关性。方法　采用免疫组织化学Max-Vision法检测210例HPV阳性液基细胞学标本及组织中HPV L1蛋白及p16INK4A的表达。结果　在各级液基细胞学标本中,HPVL1蛋白阳性率各组比较差异有统计学意义（χ2＝70.50、P＜0.005）,其中低度鳞状上皮内病变（LSIL）组最高[68 %（34／50）];p16INK4A表达阳性率随着病变级别的增高逐渐增高（13 %、28 %、52 %、100 %、100 %）,在子宫颈癌（SCC）组最高[100 %（30／30）]。HPVL1+p16INK4A -率在LSIL组中最高[32 %（16／50）];HPVL1-p16INK4A +率在SCC组最高[100 %（30／30）]。在各级别病理组织中,HPVL1蛋白表达阳性率不同,差异有统计学意义（χ2＝54.37、P＜0.005）,其中,CINⅠ级中最高[60.4 %（32／53）];p16INK4A表达阳性率随着病变级别的增高逐渐增高,在子宫颈癌组最高[100 %（28／28）]。HPVL1+p16-率在CINⅠ级中最高[45.3 %（24／53）];HPVL1-p16+率在子宫颈癌中最高[100 %（28／28）]。结论　HPVL1蛋白与p16INK4A联合检测可以区分不同的子宫颈病变,将有潜在发展与有自愈可能的病例分开,避免漏诊与过度治疗。     

Evaluation of a new p16(INK4A) ELISA test and a high-risk HPV DNA test for cervical cancer screening: results from proof-of-concept study

p16(INK4a), a cell cycle regulation protein, accumulates in abnormal epithelial cells infected with high-risk human papilloma virus (HPV). In immunostaining studies, p16(INK4a) has shown potential as a marker of high grade cervical intraepithelial neoplasia (CIN) and invasive cervical cancer. To evaluate its potential use in cervical cancer screening, we conducted a feasibility study to compare the performance of a new enzyme linked immunosorbant assay (ELISA) for p16(INK4a) (mtm laboratories, Heidelberg, Germany) to that of the Hybrid Capture 2 (hc2) test for high-risk HPV DNA for the detection of CIN3. Three hundred and nineteen women were referred from Western Washington Planned Parenthood clinics for colposcopy examination and cervical biopsy because of abnormal Pap test results. Cervical samples were obtained from study participants for p16(INK4a) ELISA, liquid-based cytology and hc2. The order (first and second) for obtaining samples for cervical cytology and p16(INK4a) ELISA changed with every other subject. Concentrations of p16(INK4a) protein were higher when the sample was taken before the cytology. The sensitivity of p16(INK4a) ELISA (concentration > or = 8 units/ml) taken as first sample was 90.0% for CIN3, and the sensitivity of HC2 taken as a second sample was 85%. In the same group, the specificity of p16(INK4a) ELISA (46.9%) was slightly better than hc2 (35.4%) Results from this proof-of-concept study suggest that p16(INK4a) ELISA has a similar sensitivity and slightly better specificity for CIN3 compared to hc2. These findings support proceeding with a larger study with samples from a population of women presenting for routine cytology screening.     

The study of the combination detection of HPV-DNA and p16INK4a in cervical lesions

The objective of this study is to detect the infection of human papillomavirus (HPV) and the expression of p16(INK4a) in cervical lesions and to investigate the interaction between hrHPV and p16(INK4a) for cervical lesions and its diagnostic efficiency. hrHPV-DNA was detected by the hybrid capture II (HC-II) system. Immunochemical method was used to detect the expression of p16(INK4a), and histopathologic test was performed to identify cervical lesions. χ(2) test and Spearman's rank correlation were used for statistical analysis. Additive effects model was used to analyze the interaction. The diagnostic sensitivity, specificity, positive predictive values, negative predictive values, accuracy, and the area under the receiver operating characteristic curve were calculated with SPSS 13.0. hrHPV and p16(INK4a) positive rate increased (P < 0.05) with histopathologic diagnosis increasing. The positive rates of hrHPV and p16(INK4a) in negative or chronic inflammation were statistically lower than that in cervical intraepithelial neoplasia (CIN)1, CIN2, CIN3, and squamous-cell carcinoma (SCC) (P < 0.05), respectively. There was a positive interaction between hrHPV and p16(INK4a), relative excess risk of interaction (RERI) was 52.49, attributable proportions of interaction (API) were 72.34%, and the synergy index (S) was 3.75. The specificity and AUC of combining hrHPV with p16(INK4a) were statistically higher than hrHPV or p16(INK4a) alone (P < 0.05). hrHPV and p16(INK4a) are useful markers for the early diagnosis of cervical lesions. A positive interaction between hrHPV and p16(INK4a) is seen. The combination of hrHPV and p16(INK4a) has a higher diagnostic accuracy than hrHPV or p16(INK4a) alone in diagnosis of cervical lesions.