The diagnostic accuracy of E6 & 7 mRNA detection as a primary screening test for the detection of severe cervical lesions.

PURPOSE

This prospective accuracy study aimed to assess the diagnostic accuracy of nucleic acid sequence amplification (NASBA) and flow cytometry for E6/7 human papillomavirus (HPV) mRNA detection as a primary screening test compared to cytology in the triage of severe cervical intraepithelial neoplasia (CIN) lesions.

METHODS

1083 women referred to our outpatient gynecology clinics for a routine Pap test were recruited. Residual material of the Pap smears was tested by NASBA and by flow cytometry for E6/7 mRNA expression. Biopsy results were used as reference standards. The accuracy indices of both techniques and of NASBA type-16 HPV were assessed for the detection of CIN2+ lesions and were compared to cytology.

RESULTS

An increased lesion severity was associated with increased positivity rates of both NASBA and flow cytometry tests (x(2), p<0.001). A positive correlation between NASBA and flow cytometry was identified when these methods were examined with the Phi coefficient (value 0.369, 95% confidence interval [95%CI] : 0.307-0.426). Furthermore, NASBA (89.7 vs 57.7%, p<0.0005) and flow cytometry (77.3 vs 57.7%, p<0.0005) exhibited higher specificity rates than cytology. However, their sensitivity rates did not exceed those of cytology (NASBA:69.8 vs 84.6%, p=0.051; flow cytometry: 69.12 vs 84.6%, p=0.043).

CONCLUSIONS

Both NASBA and flow cytometry exhibited increased specificity for the triage of CIN2+ lesions. However, their relatively lower sensitivity and higher positivity rates when compared to cytology do not make them ideal for a primary screening test. Hence, the role of mRNA detection in the screening for severe cervical lesions remains to be clarified.