Methylated DNA markers of esophageal squamous cancer and dysplasia: an international study.

Background: Discovery of methylated-DNA-markers (MDMs) of esophageal-squamous-cell-carcinoma (ESCC) has sparked interest in assessing these markers in tissue. We evaluated MDMs in ESCC from three geographically and ethnically distinct populations, and explored the feasibility of assaying MDMs from DNA obtained by swallowed-balloon-devices. Methods: MDMs were assayed in ESCC and normal tissues from the US, Iran, and China, and from exfoliative cytology specimens obtained by balloons in a Chinese population. Areas under the receiver- operating-curve (AUCs) of MDMs discriminating ESCC from normal were calculated. Random forest prediction models were built, trained on US cases and controls and calibrated to US-only controls (Model 1), and three-country controls (Model 2). Statistical tests were used to assess the relationship between dysplasia and MDM levels in balloons. Results: Extracted DNA from 333 ESCC, and 322 normal tissues were analyzed, in addition to archival DNA from 98 balloons. For ESCC, Model 1 validated in Iranian and Chinese tissues with AUCs of 0.90 and 0.87, and Model 2 yielded AUCs of 0.99, 0.96, and 0.94 in tissues from the US, Iran, and China, respectively. In Chinese balloons, MDMs showed a statistically significant trend of increasing levels with increasing grades of dysplasia (p<0.004). Conclusions: MDMs accurately discriminate ESCC from normal esophagus in tissues from high and low incidence countries. Preliminary data suggest that levels of MDMs assayed in DNA from swallowed-balloon-devices increase with dysplasia grade. Larger studies are needed to validate these results. Impact: MDMs coupled with minimally-invasive collection methods have the potential for world-wide application in ESCC screening.