BackgroundRecurrent aphthous stomatitis (RAS) is a common oral disease with unknown molecular pathogenesis. Our preliminary microarray analysis revealed the altered expression of lncRNA Cancer Susceptibility Gene 2 (CASC2) in RAS. We therefore analyzed the role of CASC2 in RAS.MethodsIn this study, plasma samples were obtained from RAS patients and healthy participants. Plasma levels of CASC2 were measured by RT-qPCR. Plasma levels of IL-6 and IL-18 were measured by enzyme-linked immunosorbent assay (ELISA). A follow-up study was performed to analyze the role of CASC2 in the recurrence of RAS.ResultsIn the present study, we found that lncRNA Cancer Susceptibility Gene 2 (CASC2), as well as pro-inflammatory factors interleukin 6 (IL-6) and interleukin 18 (IL-18), were upregulated in plasma of RAS patients compared with healthy participants. Plasma levels of lncRNA CASC2 were positively correlated with plasma levels of IL-6 and IL-18 in RAS patients but not in healthy participants. Compared with pre-treatment levels, plasma levels of lncRNA CASC2, IL-6 and IL-18 were reduced after recovery. A follow-up study showed that patients with high levels of lncRNA CASC2 had a significantly higher recurrence rate.ConclusionLncRNA CASC 2 is upregulated in RAS and predicts the recurrence.