Association between risk factors, molecular features and CpG island methylator phenotype colorectal cancer among different age groups in a Taiwanese cohort.

Background: CpG island methylator phenotype (CIMP) represents a carcinogenesis pathway of colorectal cancer (CRC) and the association between CIMP CRC, molecular features and risk factors in East Asian population is less studied.
Methods: We prospectively enrolled newly diagnosed CRC patients at the National Taiwan University Hospital. Clinicopathological data and risk factors for CRC were collected during interview. The tumour samples were subjected to CIMP, RAS/BRAF mutation and microsatellite instability tests. CIMP-high was determined when ≧3 methylated loci of p16, MINT1, MINT2, MINT31 and MLH1 were identified. Multivariate logistic regression was used to evaluate the association between risk factors and CIMP-high CRC.
Results: Compared with CIMP-low/negative CRC, CIMP-high CRC was associated with more stage IV disease, BRAF V600E mutation and high body mass index (BMI ≧ 27.5 kg/m ² ) in younger patients (age < 50 y), and more right-sided tumour, BRAF V600E mutation, MSI-high and colorectal polyp in elder patients (age ≧ 50 y). Multivariate analyses showed that BMI ≧27.5 kg/m ² was significantly associated with CIMP-high CRC in younger patients.
Conclusions: We identified distinct clinicopathological features for CIMP-high CRC among different age groups in Taiwan. Our data suggest the association between BMI ≧27.5 kg/m ² and CIMP-high CRC in patients younger than 50 years.