Colorectal cancer is a heterogeneous disease that develops via stepwise accumulation of wellcharacterized genetic and epigenetic alterations. We review the genetic changes associated with the development of pre-cancerous colorectal adenomas and their progression to tumors, as well as the effects of defective DNA repair, chromosome instability, microsatellite instability, and alterations in the serrated pathway and DNA methylation. We provide insights into the different molecular subgroups of colorectal tumors that develop via each of these different mechanisms and their associations with patient outcomes.

Background: Systemic inflammation via host-tumor interactions is currently recognized as a hallmark of cancer. The aim of this study was to evaluate the prognostic value of various combinations of inflammatory factors using preoperative blood, and to assess the clinical significance of our newly developed inflammatory score in colorectal cancer (CRC) patients. Method: In total 477 CRC patients from the discovery and validation cohorts were enrolled in this study. We assessed the predictive impact for recurrence using a combination of nine inflammatory markers in the discovery set, and focused on lymphocyte-C-reactive protein ratio (LCR) to elucidate its prognostic and predictive value for peri-operative risk in both cohorts. Results: A combination of lymphocytic count along with C-reactive protein levels demonstrated the highest correlation with recurrence compared with other parameters in CRC patients. Lower levels of preoperative LCR significantly correlated with undifferentiated histology, advanced T stage, presence of lymph node metastasis, distant metastasis, and advanced stage classification. Decreased preoperative LCR (using an optimal cut-off threshold of 6000) was an independent prognostic factor for both disease-free survival and overall survival, and emerged as an independent risk factor for postoperative complications and surgical-site infections in CRC patients. Finally, we assessed the clinical feasibility of LCR in an independent validation cohort, and confirmed that decreased preoperative LCR was an independent prognostic factor for both disease-free survival and overall survival, and was an independent predictor for postoperative complications and surgical-site infections in CRC patients. Conclusion: Preoperative LCR is a useful marker for perioperative and postoperative management of CRC patients.