Unique characteristics of CpG island methylator phenotype (CIMP) in a Chinese population with colorectal cancer

BACKGROUND: Molecular characteristics of CpG island methylator phenotype (CIMP) in colorectal cancer (CRC) have been well documented in Western, but not in Chinese, populations. METHODS: We investigated the incidence of CIMP, BRAF/KRAS mutation, and microsatellite instability (MSI) in a Chinese population with CRC (n = 401) and analysed associations between CIMP status and clinicopathological and molecular features. RESULTS: A total of 41 cases, 310 cases, and 40 cases were classified as CIMP-high, CIMP-low, and CIMP-negative, respectively. We detected a significantly low incidence of BRAF mutation in adenomas (2%) and CRC (0.7%), and a relatively low incidence of KRAS mutation (24.9%) compared with that in other populations. We also detected a relatively low incidence of CIMP-high (10.2%), which was significantly associated with younger age (≤49 years of age), female sex, and proximal tumour location. CONCLUSIONS: This study revealed unique characteristics of CIMP in a Chinese population with colorectal cancer. Developing specific CIMP markers based on unique populations or ethnic groups will further help to fully elucidate CIMP pathogenesis.