Performance of a six-methylation-marker assay on self-collected cervical samples – A feasibility study

Highlights

• GynTect methylation marker testing is well feasible on self-collected samples.

• Call rate of 95.5 % for the self-collected samples.

• Clinical results of the self-collected samples differed clearly from physician samples.

Abstract

Objectives

In high-income countries, a high proportion of cervical cancers is diagnosed in screening non-attendees. One approach to improve screening coverage is to offer self-sampling for human papillomavirus (HPV) testing. However, especially young women are often HPV positive without having a precancerous lesion in need of treatment. To improve the rather low specificity of HPV testing additional markers such as DNA-methylation can be used. The aim of this feasibility study was to examine the performance of the methylation marker assay GynTect®, comprising six methylation markers, on dry self-collected cervico-vaginal samples compared to physician-taken samples.

Methods

We recruited 89 patients from our colposcopy clinic of whom 87 qualified for the study. The women took a self-sample with the Evalyn-Brush. Afterwards the planned colposcopy was performed and smears for cytology and reference HPV testing were taken as well as a biopsy in cases of abnormalities. Physician-taken and self-collected samples were tested for HPV DNA and were analyzed with GynTect®.

Results

We obtained 95.5 % valid results for the self-collected samples which was very close to the physician-taken samples. Only about half of the self-collected samples were GynTect® positive in comparison to the physician-taken samples. GynTect® scores were significantly lower for self-collected than for physician-taken samples (p = 0.001, paired t-test). The overall concordance for GynTect® results was moderate (kappa 0.394; p < 0.001). For HPV testing we obtained a good concordance (kappa 0.586; p < 0.001). The GynTect® results for the self-collected samples showed a sensitivity for the detection of cervical intraepithelial neoplasia 2 or worse (CIN2+) of 26.1 % (95 %-CI: 0.13−0.46) and a specificity of 95.6 % (95 %-CI: 0.85−0.99), in comparison to a sensitivity of 45.5 % (95 %-CI: 0.27−0.65) and a specificity of 78.3 % (95 %-CI: 0.64−0.88) for the physician-taken samples.

Conclusions

GynTect® methylation marker testing has a satisfactory amount of valid results on self-collected samples. However, the results of the self-collected samples differed clearly in comparison to the reference samples. To justify an application in screening, a larger study with more cases of high-grade cervical dysplasia and HPV positive patients will be needed.

Introduction

Cervical cancer is the fourth most common cancer in women worldwide (Ferlay et al., 2018). The incidence was sharply reduced by screening programs (Bengt et al., 2008; Ronco et al., 2010). Studies showed that an organized screening based on testing of high-risk human papilloma virus genotypes (hrHPV) is superior to the traditional cytology screening (PAP) to detect precancers (Ronco et al., 2014, 2010). The problem remains, that in developed countries a high number of cervical cancer cases is diagnosed in screening non-attendees (Marquardt et al., 2011; Bos et al., 2006; Leyden, 2005). To improve the screening coverage one approach is offering self-sampling for non-attending women which is feasible at home (Gök et al., 2010; Bais et al., 2007; Elfström et al., 2019; Arbyn and Castle, 2015; Tranberg et al., 2018a, b). So far studies have shown that self-collected samples cannot be reliably analyzed by cytology but with HPV testing (Tranberg et al., 2018a, b; Arbyn et al., 2014; Polman et al., 2019; Jentschke et al., 2013; Poljak et al., 2015).

A lot of young women are HPV-positive without having a precancerous lesion, so that HPV testing of those self-collected samples alone would cause a lot of unnecessary control examinations with a high loss to follow-up. To increase the rather low specificity of HPV testing additional markers such as DNA methylation can be used (Clarke et al., 2017; Boers et al., 2016). Methylation marker tests serve as triage method applicable directly on the self-sample (Eijsink et al., 2010; Boers et al., 2014; Luttmer et al., 2016).

The GynTect® methylation marker assay (oncgnostics GmbH, Jena, Germany) comprises six methylation markers: ASTN1, DLX1, ITGA4, RXFP3, SOX17, ZNF671. The final evaluation for each sample includes a weighting for each marker. GynTect® is CE certified for medical scrapes and has shown a good overall performance regarding sensitivity and specificity for high grade CIN (Schmitz et al., 2017, 2018).

In this pilot study we wanted to examine the performance of the GynTect® assay on dry self-collected cervico-vaginal samples in comparison to physician-taken samples to show whether the assay can be reliably performed directly on self-collected material to predict high-grade CIN and thus the need for close monitoring or treatment.