CpG Island Methylator Phenotype May Predict Poor Overall Survival of Patients with Stage IV Colorectal Cancer.

OBJECTIVE: We aimed to study the prognostic role of CpG island methylator phenotype (CIMP) in patients with different stages of colorectal cancer (CRC). MATERIAL AND METHODS: We analyzed CIMP in stage I-IV CRC specimens from patients who were diagnosed between 2005 and 2013. CIMP status was determined using a 5-gene MethyLight-based assay. The clinicopathologic characteristics were reviewed and the overall survival (OS) was compared between patients with CIMP-high CRC and those with CIMP-low/negative CRC. RESULTS: Among 450 CRC specimens with successfully determined CIMP statuses, 74 (16.4%) were CIMP-high CRC. Although there was no difference in OS between patients with CIMP-high and CIMP-low/negative CRC across all stages (p = 0.4526), intriguingly, patients with stage IV CIMP-high CRC had significantly worse OS than those with stage IV CIMP-low/negative CRC (p = 0.0047). In a multivariate analysis, CIMP status remained an independent prognostic factor for overall mortality (HR = 5.60, 95% CI: 2.12-14.79, p = 0.0005) in metastatic CRC after adjusting for clinicopathologic variables and anti-cancer therapies. CONCLUSION: Our results revealed that the presence of CIMP independently predicts poor OS in patients with stage IV CRC.