Clinical significance of primary tumour location in colorectal cancer — a review

Abstract

Colorectal cancer (CRC) is one of the most common malignant neoplasms worldwide. The heterogeneous course of disease, as well as, genetic and molecular differences between tumours localized in different parts of the large intestine, resulted in an attempt to evaluate the significance of the primary tumour location and divide colorectal cancer into right- and left-sided. The results of the retrospective analyses of the phase III studies indicate that the right-sided location is a negative prognostic factor in stage IV and III of disease. The benefit of adding an anti-EGFR antibody to the first-line palliative chemotherapy was clearly demonstrated for patients with primary tumour located on the left side and the effect of treatment seems to be better than anti-VEGF therapy combined with chemotherapy. Treatement results of patients with right-sided primary tumour location are worse regardless of the type of treatment. In patients with right-sided cancer, it seems that bevacizumab treatment might be more beneficial in comparison with anti-EGFR therapy, although these suggestions are based on small groups of patients. The efficacy of bevacizumab seems to be independent of primary tumour location. It is still unclear whether the primary tumour location should be considered as an independent prognostic or predictive factor, or rather it is necessary to look for specific genetic and molecular disorders responsible for demonstrated and possible differences.