Expression characteristics of tumors as prognostic and predictive markers for resectable and locally advanced colorectal cancer

Background. The risks of recurrence and death in patients with colorectal cancer (CRC) can vary significantly, even among patients with similar clinicopathological features, due to the high level of tumor heterogeneity. Existing molecular classifications have relatively limited value. Gene signatures identified through whole-exome / whole-transcriptome analyses may play a more significant role. Aim. To systematize literature data on expression signatures and describe their prognostic and predictive value in the context of non-metastatic CRC. Results. This review describes contemporary aspects of personalized approaches in the treatment of CRC applied in clinical practice: mutational and microsatellite status, the significance of the primary tumor's location. Data on multi-gene signatures and tumor expression characteristics are also presented. Several signatures allow predicting the risk of recurrence, disease-free, and overall survival in resectable and locally advanced CRC. Additionally, the correlation between drug sensitivity and DNA repair gene signatures is demonstrated. Data on the correlation of expression signatures with proteins, phosphoproteins, and their role as prognostic and predictive factors in non-metastatic CRC are provided. Conclusion. The practical application of gene signatures currently lacks significance. Due to the scattered nature of data and the wide variety of examined signatures, making meaningful conclusions about their practical value is impossible. However, it is possible that in the future, the use of gene signatures will lead to a more accurate prognosis, new approaches to drug therapy, and improved outcomes for patients with CRC.