Thirteen-gene DNA methylation analysis of oral brushing samples: A potential surveillance tool for periodic monitoring of treated patients with oral cancer

Background: We evaluated the prognostic role of 13-gene DNA methylation analysis by oral brushing repeatedly performed during the follow-up of patients surgically treated for oral cancer.Methods: This is a nested case-control study including 61 patients for a total of 64 outcomes (2/61 patients experienced multiple relapses). Samples were collected at baseline (4-10 months after OSCC resection) and repeatedly every 4-10 months until relapse or death. DNA methylation scores were classified as persistently positive, persistently negative, or mixed.Results: Twenty cases who had persistently positive scores and 30 cases with mixed scores had, respectively, an almost 42-fold (p < 0.001) and 32-fold (p = 0.006) higher likelihood of relapse, compared to 14 patients with persistently negative scores. The last score before reoccurrence was positive in 18/19 secondary events.Conclusions: The 13-gene DNA methylation analysis may be considered for the surveillance of patients treated for oral carcinoma.