Anal cancer is an increasing problem in HIV+ men who have sex with men (MSM) and like cervical cancer caused by high-risk HPV and preceded by precursor lesions: anal intraepithelial neoplasia (AIN; graded 1 to 3). Currently, screening for AIN by high-resolution anoscopy (HRA) leads to over-referral and overtreatment. DNA methylation analysis is a promising pre-screening tool to detect cervical (pre)cancer, but has not been studied in the clinical management of anal (pre-)cancer in HIV+ MSM. We set out to find methylation markers that enable the detection of anal cancer or AIN in need of treatment.
A series of FFPE tissue samples of HIV+ men with anal squamous cell carcinoma (SCC; n=18), AIN3 (n=24), AIN2 (n=40) and men without evidence of AIN2 or worse (normal + AIN1; n=29) were analysed for DNA methylation of six genes known to display hypermethylation during HPV-induced carcinogenesis using quantitative methylation-specific PCR (qMSP). Univariable and multivariable logistic regression was used to determine the performance of the methylation markers for the detection of high-risk lesions.
Methylation levels of all six genes increased significantly with severity of disease, with up to 95% positivity in SCC. Analysis of methylation marker combinations yielded an area under the ROC curve of 0,85 for detecting AIN3 or worse.
We identified a panel of methylation markers that provide an attractive triage tool to discriminate HIV+ MSM with clinically irrelevant precursor lesions (low cancer risk) from those with lesions in need of treatment.