Detection of human papillomavirus in matched cervical smears and biopsy specimens by non-isotopic in situ hybridisation

Cervical biopsies and cytological smears - a comparison of sample materials in HPV diagnostics

BACKGROUND

Cervical cancer is causally related to cervical infections by oncogenic human papillomavirus (HPV) genotypes. To improve the quality of diagnosis evaluation of screening methods and their HPV type detection rate is an important part for this item.

OBJECTIVES

Two different cervical specimens of the same patients were analysed simultaneously with molecular HPV subtyping methods to find the most sensitive sample material for cervical cancer screening.

STUDY DESIGN

Biopsy specimens and cytological smears of the cervix of 443 patients were analysed for human papilloma virus (HPV) subtyping by a macroarray from Chipron, Germany, which allows a differentiation of 16 high and 16 low risk types. Results were compared for reliability and differences were studied.

RESULTS

Both sample material groups showed HPV conformity of 70%, 23% more subtypes could be detected in smears in contrary to biopsies but only 6% vice versa. 14 biopsies and 7 smears were HPV negative although the concerning second sample type of the patients was HPV positive. HPV 16 as one of the most relevant subtypes in cervical cancer pathogenesis was missed in the biopsies' group with 34.3% out of 35 HPV 16 positive smear cases, whereas only one smear failed to discover this subtype contrariwise.

CONCLUSION

Comparison of the examination results shows that subtyping of smear samples is able to detect more subtypes than by biopsy specimens. The probability to underdiagnose HPV 16 and to get a false negative result in bioptic sample material favours smear as method of choice for HPV subtyping.

Immunohistochemical expression of mdm2 and p21WAF1 in invasive cervical cancer: correlation with p53 protein and high risk HPV infection

AIM

To investigate the immunocytochemical staining pattern of mdm2 and p21WAF1 proteins in invasive cervical cancer and to determine its relation with the expression of p53 and with the high risk HPV infection.

METHODS

Immunocytochemistry for p53, mdm2, and p21WAF1 was performed in 31 paraffin embedded sections of invasive cervical cancer. The results were assessed by image analysis, evaluating for each protein the optical density of the immunostained area, scored as percentage of the total nuclear area. The presence of high risk human papillomavirus (HPV) infection was detected by using the polymerase chain reaction.

RESULTS

Immunostaining for both mdm2 and p21WAF1 was correlated with p53 expression; however, the correlation between p53 and mdm2 (R = 0.49; p < 0.01) was more significant than between p53 and p21WAF1 (R = 0.31; p < 0.05); the less stringent correlation between p53 and p21WAF1 might reflect the p53 independent mechanisms of p21WAF1 induction. Similar average levels of p53, mdm2, and p21WAF1 immunostaining were found in the presence or absence of high risk HPV-DNA, without significant differences between the two groups.

CONCLUSIONS

These data suggest that mdm2 and p21WAF1 proteins are expressed in invasive cervical cancer and that their immunocytochemical staining pattern is not abrogated by the presence of high risk HPV genomic sequences.

Human papillomavirus status in the prediction of high-grade cervical intraepithelial neoplasia in patients with persistent low-grade cervical cytological abnormalities

The role of human papillomavirus (HPV) detection in the management of patients with persistent low-grade (mild dyskaryosis or less) cervical cytological abnormalities is unclear. We have analysed cytological material from 167 such patients both cytologically and by non-isotopic in situ hybridisation (NISH) for HPV 16, 18, 31 and 33 and consensus primer polymerase chain reaction (PCR) amplification followed by both generic and specific typing for these HPV types. Cervical intraepithelial neoplasia (CIN) 2 or 3 was present in 40 of 167 patients (23.9%), and the positive predictive values (PPVs) for the presence of CIN 2 or 3, of moderate or severe dyskaryosis at repeat cytology and an HPV-positive NISH and generic PCR signal were 100%, 66% and 42% respectively. The corresponding sensitivities were 48%, 68% and 87%. Addition of cytology to molecular analysis improved both PPV and sensitivity, the best combination being NISH and cytopathology (PPV 71%, sensitivity 87%). These data demonstrate that the presence of CIN 2 or 3 in patients with mild cytological abnormalities can be predicted by molecular detection of HPV in some cases, particularly when combined with cytological analysis. However, the magnitude of this prediction is dependent on the population of patients studied, and the clinical role of this approach therefore remains to be defined.

Comparative analysis of human papillomavirus detection by dot blot hybridisation and non-isotopic in situ hybridisation

AIMS

To determine the relative diagnostic performance of non-isotopic in situ hybridisation (NISH) and a dot-blot assay for detecting human papillomavirus (HPV) on exfoliated cervical cells; and to correlate the results with cytopathological assessment.

METHODS

Cervical smears and cytological samples were obtained from 122 patients during the same clinical examination and the presence of HPV sequences determined by NISH and dot-blot analysis, respectively.

RESULTS

Dot-blot analysis gave an autoradiographic signal in 15 of 121 (12.4%) cases, while NISH detected viral genomes in 38 of 114 (33.3%) cases. Even in the presence of koilocytosis, where vegetative replication of the virus occurs, NISH was positive in over twice as many cases as dot-blot analysis (NISH 90%, dot-blot 40%), while in smears within normal cytological limits, where the viral copy number is likely to be considerably lower, the differences were more striking (NISH 31%, dot-blot 5%).

CONCLUSIONS

These data show that NISH on cytological smears is more sensitive than a standardised dot-blot hybridisation assay for detecting HPV infection in cytological material and is therefore a more appropriate screening tool.