Diagnostic Performance of Host and Viral DNA Methylation Analysis in the Identification of Anal Intraepithelial Neoplasia and Cancer: Systematic Review and Meta-Analysis.

INTRODUCTION

DNA methylation-based biomarkers have been investigated as useful tools in the carcinogenesis process, including the triage of HPV-associated cancers. In this context, we conducted a systematic review and meta-analysis focused on evaluating the changes in the level of DNA methylation in cases of pre-cancerous (i.e., anal intraepithelial neoplasia, AIN-1, -2., -3) and cancerous (i.e., squamous cell carcinoma, SCC) anal lesions.

METHODS

A research in the PubMed, Scopus, and Web of Science databases was carried out, following the PRISMA 2020 protocol, using the following keywords: "anal cancer", "anal intraepithelial neoplasia", "methylation", and "epigenetic". All observational studies that reported the level of DNA methylation by grade of anal lesions and for different target genes were included. The QUADAS-2 tool was used to assess the studies' quality, whereas pooled prevalence, sensitivity, specificity, and diagnostic odds ratio (DOR) were employed to verify the accuracy of the test in the detection of high-grade lesions.

RESULTS

Eight studies met the inclusion criteria, involving a total of 1555 clinical samples. The prevalence of methylation-positive samples by histological grading was 27%, 45%, 54%, and 98% for AIN1, AIN2, AIN3, and SCC, respectively. Similar results were observed for the DOR, with higher ORs in more severe lesions. The pooled AUC (95%CI) for the diagnosis of ≥AIN2 was 0.68 (0.63-0.73).

CONCLUSIONS

The present review and meta-analysis support the introduction of DNA methylation-based biomarkers in the triage of subjects with low-grade anal lesions and in the monitoring of treatment outcomes. Standardized protocols and a prospective study design are needed to implement methylation tests in clinical practice.