Proliferation patterns of cervical cells as visualized in Leiden liquid cytology slides

Implementing specificity of HPV-DNA primary screening in a successful organised cervical cancer prevention programme

OBJECTIVE

This two-arm longitudinal study was performed within a regional organized cervical-cancer-prevention program in which HPV-DNA test is used in primary screening. The aim was to analyze the diagnostic performances of p16INK4a/Ki-67 dual-test and E6/E7-mRNA test in identifying CIN2+ lesion among HPV-DNA positive (HPV-DNAve) women triaged for LSIL-or-worse liquid based cytology (LBC).

METHODS

Thirty-six thousand thirty-one women participated to HPV-DNA screening program pilot study. Three thousand six hundred forty-one resulted HPV-DNAve; among these, 43% were LSIL-or-worse (LSIL+). HPV-DNAve/LSIL+ patients were submitted to colposcopy and histological assessment of any visible lesions. Dual-test was performed on 794 residual LBC specimens. In 405 cases, dual-test result was related to histology, considering CIN2+ as endpoint. mRNA test has been carried out retrospectively, on a subset of 173 residual LBC specimens.

RESULTS

Agreement between dual-test and histological diagnosis was 59%. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of cytology-plus-dual-test approach were 62.3%, 76.8%, 63.1% and 84.2%, respectively. Dual-test improved specificity, PPV and NPV of cytological triage Agreement between mRNA testing and histology was 65%. Cytology-plus mRNA testing showing sensitivity, specificity, PPV and NPV reaching 32.1%, 94.9%, 75% and 50%, respectively; implemented specificity and PPV of cytology alone in triaging DNA-ve/LSIL+ patients (p<0.01).

CONCLUSIONS

We provided promising data indicating the important role that p16(INK4)/Ki-67 dual-test, and mostly E6/E7 mRNA test, might have in triaging HPV-DNAve. These approaches would exclude the occurrence of cervical cancer and would avoid overtreatment, at the same time. Further longitudinal analysis has to be considered.

Theory and practice of combining coagulant fixation and microwave histoprocessing

The German, F. Blum, introduced formalin as a fixative in 1893. Formalin rapidly became popular for hardening and preserving gross human and animal specimens. As a result, microscopy for diagnostic pathology by combining paraffin embedding and formalin fixation was developed. Alcohol-based fixatives have coagulation of proteins as their main preservative effect. Because there is no cross-linking, immunostaining is not compromised, and DNA and RNA is not damaged. Ethyl alcohol was used by Dutch scientists of the 18th century, but was replaced by the cheaper formalin. Addition of low molecular weight polyethylene glycol (PEG) optimized the coagulant fixative, Kryofix. The polyethylene glycol prevents excessive hardening and enhances the speed of coagulation of proteins. Kryofix was used on a large scale for skin biopsies in Leiden between 1987 and 2001. DNA preservation by the formulated coagulant fixative, BoonFix, is related to the concentration of ethyl alcohol, PEG and acetic acid. BoonFix has been used since 2004 in Leiden for over 40,000 diagnostic skin biopsies and more than 100,000 cervical samples. A literature review and three decades of experience with coagulant, formalin-free fixatives in pathology suggest that when health authorities realize that formalin invalidates expensive tests, it might eventually be eliminated legislatively from diagnostic pathology. Finally, coagulant fixation is optimal for microwave histoprocessing where ethyl alcohol is followed by isopropanol.

Efficiency of an inexpensive liquid-based cytology performed by cytocentrifugations: a comparative study using the histology as reference standard

BACKGROUND

Although liquid-based cytology (LBC) is now recommended for cervical cancer screening, it requires expensive automated devices and materials. To evaluate the efficiency of inexpensive LBC methods relying on an inexpensive fixative liquid, Easyfix, we compared the results obtained by the liquid-based cytology (LBC) diagnoses performed by cytocentrifugations (Papspin and Turbitec) with those obtained by histology. Furthermore, we evaluated the efficiency of the fixative liquid, Easyfix, to preserve HPV DNA in the collected samples.

METHOD

266 LBC were compared with 174 colposcopies and 91 Loop Electrosurgical Excision Procedure (LEEP). Among the LBC, 51 were performed using the Papspin system and 215 were performed using the Turbitec system. To control the quality of the preservation liquid, Easyfix, we correlated the results of HCII assays with those of HPV PCR.

RESULTS

For Papspin and Turbitec systems, the sensitivities were respectively 82.6% (95% CI: 61.2-95.0%, p < 0.001) and 75.0% (95% CI: 64.4-89.8%, p < 0.001) and the specificities were 92.6% (95%CI: 76.5-99.1%, p < 0.001) and 96.2% (95% CI: 91.3-98.7%, p < 0.001). We find no statistical difference between the results of the both systems (p = ns). The sensitivity of the HCII was 86.4% (95% IC: 77.4-92.8%, p < 0.001) and the specificity was 39.4% (95% CI: 31.2-48.1%, p < 0.001). The comparison between HCII and HPV-PCR shows a good correlation: the kappa was 0.89.

CONCLUSION

LBC performed by cytocentrifugations are inexpensive, reduce inadequate smears, show excellent efficiency and allow HPV detection by molecular biology.