Frequent BRAF mutation in early-onset colorectal cancer in Taiwan: Association with distinct clinicopathological and molecular features and poor clinical outcome

Background: Occurrence of early-onset colorectal cancer (EOCRC) under the age of 30 is very rare and the molecular characteristics are poorly understood. A low BRAF mutation rate has been noted in several studies of EOCRC from Western countries. Aims: To determine the clinicopathological and molecular features of EOCRCs in Taiwan. Methods: KRAS/BRAF gene mutation, mismatch repair protein immunohistochemistry, microsatellite instability and CpG island methylation phenotype analyses were examined to determine the molecular characteristics of EOCRC. Results: Sixty-six patients with EOCRC at our hospital between 2000 and 2012 were studied. BRAF mutation was detected in 11 of the 59 tumours analysed (19%) and the rate was significantly higher than the overall BRAF mutation rate of colorectal cancer in patients older than 30 years (p