A change of the current screening algorithms to a HPV-based screening setting is discussed in several countries due to higher sensitivity of HPV testing compared to cytology. Reliable triage methods are, however, essential in such a setting to avoid overtreatment and higher screening costs. Specific DNA methylation patterns may provide a suitable tool especially with regard to keeping false positive rates low.
Cervical scrapes collected in PreservCyt® from women with cervical cancer (5 cases), CIN 1-3 (74 cases) and normal cytology (Pap I; 200 cases) were assessed for methylation of the marker regions ASTN1, DLX1, ITGA4, RXFP3, SOX17, and ZNF671 (GynTect® assay). All samples had previously been tested for HPV by the cobas® HPV assay. Moreover, for all patients with CIN or cancer and for 59 of 200 patients with Pap I data for p16/Ki67 dual staining (CINtec Plus® test) were available.
All samples from women with cervical cancer, 61.2% of CIN3, 44.4% of CIN2 and 20.0% of CIN1 cases were scored positive for the GynTect methylation assay. The specificity within the Pap I group was 98.5%, thus showing an exceptionally low false-positive rate. Overall, the number of methylated marker regions increased proportionally to lesion severity, which is in contrast to CINtec Plus® and cobas® HPV, of which both detect all CINs irrespective of severity grade. Specificity of CINtec Plus in the Pap I group was similar, even though the tested cohort was smaller. We plan to have CINtec Plus results for all 200 Pap I samples before the Eurogin conference. Specificity of the cobas HPV in the Pap I group was 92%.
DNA methylation analysis of the above marker panel (GynTect® test) in cervical scrapes consistently detects cervical cancer and the majority of CIN3 as well as a subset of CIN1/2 lesions, whereas the positivity rate among cytology-normal samples is extraordinarily low. Altogether, the GynTect® assay based on detection of six methylation markers may provide an excellent tool for triage within cervical cancer screening.