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

ABSTRACT

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 (NASBA69.8 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.