The colorectum is divided into proximal and distal regions based on differences in embryonic origin, physiological functions and gene expression. Colorectal cancer is heterogeneous depending on its location: for example, proximal tumors have a higher mortality than distal tumors. It is not known, however, whether molecular events contribute to the differences in cancers that arise from conventional adenomas.

Timothy Su, MD, PhD, Martha Shrubsole, PhD, and colleagues evaluated a panel of eight biomarkers – selected because of their importance in colorectal tumorigenesis – in proximal and distal advanced conventional adenomas removed during colonoscopy.

The investigators found no significant differences between proximal and distal adenomas for any biomarker. Biomarkers did vary based on other features such as adenoma size, villous component and synchronousness (related to malignant potential).

The study, reported in the February issue of the journal Molecular Carcinogenesis suggests similarly important and synergistic roles for the Wnt/beta–catenin and TGF–beta pathways in both proximal and distal colorectum, which may have implications for colorectal cancer prevention.