The role of (m)SEPT9 in screening, diagnosis, and recurrence monitoring of colorectal cancer

BACKGROUND: The application of circulating, cell-free, methylated Septin9 ((m)SEPT9) DNA in screening and recurrence monitoring is highly promising. CpG island methylator phenotype (CIMP) is associated with microsatellite instability (MSI). The present study was performed to determine the diagnostic accuracy of (m)SEPT9 for colorectal cancer (CRC) and to evaluate its utility in CRC screening and recurrence monitoring. METHODS: For screening and diagnosis of CRC, peripheral (m)SEPT9 detection and fecal occult blood test (FOBT) were performed in 650 subjects, then the level of CEA, CA19–9 and CA724 was quantified in 173 subjects. Clinicopathological parameters and mismatch repair protein were detected among subjects with CRC. For recurrence monitoring of CRC, the sensitivity of (m)SEPT9 of 70 subjects was compared with tumor markers and contrast enhanced computed tomography (CECT). RESULTS: Seventy-three percent of CRC patients were (m)SEPT9-positive at 94.5% specificity, and 17.1% of patients with intestinal polyps and adenoma were (m)SEPT9-positive at 94.5% specificity, which were higher than FOBT for the screening of CRC. The sensitivity and specificity of (m)SEPT9 for diagnosis and recurrence monitoring were higher than that of CEA, CA19–9 and CA724. The combined detection of (m)SEPT9 and CECT enhanced the sensitivity for recurrence monitoring. Pre-therapeutic levels of (m)SEPT9 were strongly associated with TNM stage, Dukes stages and mismatch repair deficiency (dMMR). CONCLUSIONS: (m)SEPT9 analysis might be popularized as a routine biomarker for CRC screening. The combined detection of (m)SEPT9 and CECT can play an important role for recurrence monitoring. CIMP was highly associated with the pathological stage of CRC and dMMR. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12885-019-5663-8) contains supplementary material, which is available to authorized users.