Site-specific use of molecular markers could be a promising prognostic tool in colorectal cancer

Proximal and distal colorectal carcinomas (CRCs) are generally considered as genetically and clinicopathologically distinct disease entities. Tumor location has been proposed as an additional prognostic indicator and -more recently- as a factor with significant influence on the prognostic value of particular molecular markers and/or combination of markers (KRAS, MSI, APC/MSI), allowing the discrimination of specific disease subsets with considerably disparate outcome and the identification of high risk cases. This article examines the clinical importance of particular recent proposals on this specific issue. Their strengths and limitations, as well as issues requiring further elucidation and practical problems hampering their clinical implementation are briefly discussed. Moreover, some suggestions intending to improve research methodology on this specific theme and to render the clinical use of this novel approach more effective and feasible, are presented. Hopefully, the assessment of certain molecular markers in a site-specific fashion could be another step towards personalized management of CRC, improving and complementing the molecular classification of the disease.