الفهرس 
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Abstract
Cervical cancer is the second most common and the fifth deadliest cancer in women.It affects about 16 per 100,000 and kills about 9 per 100,000 womenper year. Approximately 80% of cervical cancers occur in developing countries. In 2008, it was estimated that there were 473,000 cases of cervical cancer, and 253,500 deaths per year.
HPV infection is associated with virtually all cases of cervical cancer. It is among the most commonly sexually transmitted diseases. Most women clear the infection within two years without complications. On the other hand, long term infection with high-risk strains of HPV can lead to the development of cervical cancer.
HPV contains a small, circular, double stranded D.N.A. genome. The HPV genome contains at least two genes whose protein products function as oncogenes.These genes are called E6 and E7. The E6 protein stimulates p53 protein degradation or inactivates it thus preventing cell cycle arrest or apoptosis. The E7 protein, on the other hand, binds to the retinoblastoma gene product (RB), resulting in its functional inactivation thus leading to increased cell division.
The existence of precursor lesions for invasive cervical cancer has been recognized for over a century. The term Carcinoma in situ was used to refer to these intraepithelial cervical lesions.
Cervical cancer and CIN, but not other cervical epithelia, express high levels of the cyclin-dependent kinase inhibitor p16 (INK4A). p16(INK4A) exerts its anti-proliferative effects and deccelerates the cell cycle by binding to and inhibiting the actions of CDK4 and 6,involved in the phosphorylation of the retinoblastoma protein (RB). Expression of E6 and E7 oncogenes of high-risk (HR) human papillomavirus (HPV), affecting the RB-p16 pathway, leads to p16 up-regulation. In addition, the p16 gene codes for a tumor suppressor protein which acts as a stabilizer for the tumor suppressor product of the p53 gene. These two ”p genes” together play important roles in regulating the cell cycle.
Heat shock proteins (Hsps) are over-expressed in a wide range of human cancers. Among Hsps associated with higher differentiation is Hsp27 in squamous carcinomas (uterine cervix, oral epithelium). Studies have indicated that Hsp27 is expressed by squamous cell carcinoma of the uterine cervix, and that it may be a diagnostic marker for cervical intraepithelial neoplasia (CIN) and carcinoma.
Inclusion of HPV status as a component of emerging molecular staging systems is compelling, and routine HPV assessment will soon become part of the standard pathological evaluation.
Highly sensitive methods for detecting HPV D.N.A. have been recently developed, the most sensitive of which is the PCR method.
The present study aimed at assessing the reproducibility of p16INK4A as well as Hsp27 immunohistochemical staining in the diagnosis of cervical intraepithelial neoplasia and squamous cell carcinoma, as well as comparing the Human papillomavirus polymerase chain reaction and p16INK4A immunohistochemistry in the detection of Human papillomavirus associated cervical intraepithelial neoplasia and squamous cell carcinoma.
The present study was a retrospective one undertaken on archival biopsy samples of cervical intraepithelial neoplasia (CIN) and squamous cell carcinoma (SCC).
The study comprised fifty formalin-fixed, paraffin-embedded samples, forty-six of which were part of total hysterectomy operations, while the remaining four were D&C samples. Five normal cervical tissue samples were also included as control.
All samples were subjected to the following:-
(I) Routine Hematoxylin and Eosin staining for re-evaluation and diagnosis according to the World Health Organization criteria.
(II) Immunohistochemical evaluation for the detection of p16(INK4A) proteinand Hsp27 expression.
(III) Molecular detection, using polymerase chain reaction (PCR), of either presence or absence of high-risk human papillomavirus (HRHPV) D.N.A.
The CIN samples were altogether eight samples and were found to be two samples of CINI, two of CINII, and four samples of CINIII. On the other hand, for the invasive squamous cell carcinoma (SCC) samples, the majority, namely eighteen samples, were of moderately-differentiated SCC, twelve of which were non-keratinizing, while only six were keratinizing. Fourteen samples were poorly-differentiated, non-keratinizing, while two other samples were poorly-differentiated papillary squamous cell carcinomas. Six samples were well-differentiated keratinizing squamous cell carcinomas. Only two samples were of squamous cell carcinoma variants, one of the basaloid and the other of the clear cell variant.
All five non-malignant samples, serving as control cases, were p16(INK4A) negative except for one case which showed weak cytoplasmic immunoreactivity.
p16(INK4A) immunoreactive cells demonstrated both nuclear as well as cytoplasmic reactivity, yet nuclear staining was significantly much more prominent.
The degree of p16(INK4A) immunohistochemical expression correlated well with the degree of cervical neoplasia.
p16(INK4A) was markedly up-regulated in the higher grades of cervical intraepithelial neoplasia as compared to the normal cervix. Furthermore, as one progressed from CINIII to invasive squamous cell carcinoma, the difference in p16(INK4A) expression was statistically significant (p-value < 0.05).
In addition, p16(INK4A) positivity had a sensitivity (true positive results) of 88% and a specificity (true negative results) of 100% for the identification of CINIII or S.C.C. lesions.
There was a progressive increase in the positivity percentage as well as staining intensity through increasing grades of cervical dysplasia and invasive squamous cell carcinoma.
Hsp27 immunoreactivity was seen as a diffuse cytoplasmic reaction. Rare nuclear staining was also seen.
No significant variation in either the pattern or the intensity of Hsp27 immunolabeling was recorded from NN to S.C.C. Furthermore, Hsp27 immunolabeling was significantly up-regulated in the well-differentiated S.C.C. lesions and down-regulated in those that were morphologically poorly-differentiated.
In addition, Hsp27 positivity had a sensitivity (true positive results) of 96% and a specificity (true negative results) of 60% for the identification of CINIII or S.C.C. lesions.
HPV infection was detected in 72%(36/50) of the samples by PCR technique. Considering the dysplastic samples, 74.5%(34/45) presented HPV D.N.A. Furthermore, the detection rate for HPV infection was higher as the severity of the lesions increased.
HPV 16 was detected in 25% of low-grade dysplastic lesions and in 25% and 16.2% of high-grade dysplastic lesions and invasive S.C.C cases respectively. On the other hand, HPV 18 was detected in only 8.1% of the invasive S.C.C. samples as well as in eight co-infected samples. Accordingly, HPV 16 was the virus type more frequently detected.
The sensitivity (true positive results) of p16(INK4A) for HPV D.N.A. detection was 90%. The specificity (true negative results), on the other hand, was 50%. In addition, there was significant statistical correlation between HPV positivity and p16(INK4A) expression.