This is the first prospective, population-based IBD epidemiological study in a developed region of China. The incidence of IBD is similar to that in Japan and Hong Kong but lower than that in South Korea and Western countries.

SEPT9 gene methylation was validated as a biomarker for colorectal cancer (CRC) for >10 years and available as the Epi proColon test as an aid in CRC detection for >6 years. It was proven to be an accurate, reliable, fast, and convenient molecular test. In this opportunistic screening study, we validated a further simplified SEPT9 gene methylation assay in 1031 subjects in Chinese hospitals. The sensitivity for CRC detection was 76.6% at a specificity of 95.9%, and the results showed a satisfactory detection rate for each CRC stage, including early stages. The new SEPT9 assay, with enhanced technical simplicity, convenience, and lower cost, did not differ in performance compared with Epi proColon 2.0, the commercialized SEPT9 assay. The CRC detection sensitivity was further enhanced when the assay was combined with carcinoembryonic antigen (sensitivity, 86.4%) or fecal immunochemical test (sensitivity, 94.4%), suggesting that the combined tests may be an effective option for future opportunistic screening. In brief, our study has validated a new SEPT9 assay and combined testing as an aid in cancer detection, providing a new approach for opportunistic CRC screening.

We confirmed that NUDT15 c.415C>T, c.36_37insGGAGTC, and c.52G>A variants were risk factors for thiopurine-induced leukopenia. Combined detection of the 3 variants could increase the predictive sensitivity of thiopurine-induced leukopenia and help to distinguish early leukopenia in heterozygote of c.415C>T in Chinese patients with IBD. Treatment monitoring by NUDT15 variants may be promising in individualized therapy.